Exactly. However, only because Solas doesn't have a kiss-whenever-scene or a sex-scene doesn't mean the romance is shorter. Both might be deliberate decisions to allow roleplayers a "more intellectual" relationship without dominating physical intimacy. And if we assume this and just look at the interactions/content of Solas vs. Cullen, the case is pretty clear:
* full Cullen content:
(44 mins)
* full Solas content:
(65 mins)
Solas gets to say more, is included in more scenes, has the more creative and inventive romance scenes, gets more significant kiss scenes (I cannot prove this but it seems like it) and is overall more important. Plus he ends the friggin' game with a bang. I really don't see why people keep complaining just because they don't get 1.5 seconds of a half-naked back bending over a shadow until fade-out or something.
Sometimes mistakes (are supposed to) happen.
I mean, sure, NDA and stuff. But this leak did benefit DAI by fueling the hype before release tbh. Then again I might tend to falsely assume clever PR rather than human stupidity, who knows.
Personally, Solas may get more content, but I think that comes with the territory of being a companion rather than an adviser. You can take him to more places, hear party banter, hear his comments on various places you're visiting, hear his opinions on main story areas you're visiting (like the Temple of Mythal and the Well of Sorrows), etc.
As far as romance-specific content, especially romantic cutscenes, there's technically less. If only just because he was added last-minute on a shoestring budget, so all but the last the romantic cutscenes were piggy-backing off the scenes everyone gets. The first time you talk to him in Haven and he says, "Blessed hero sent to save us all," the first time you talk to him in Skyhold and he takes you to Haven in the Fade (Fade-tongue!), the balcony scene where he asks if your mark has changed you (real kiss!), and then the scene right after the Temple of Mythal where he's either happy things worked out or angry that you drank from the Well.
The scene after "Come with me, vhenan!" is technically the only purely unique romance scene Solasmancers get, while most companions get at least one or two, usually more. Contrast Cullen, an adviser, and I think you technically get three unique romance scenes/places. The first kiss on the battlements, then the scene where he takes you to the lake where he grew up and tries to give you his lucky coin, and then that marvelous scene where he spreads you out like a map on his desk (
) followed by the headbutt-of-love scene (
). And then, of course, you get the romantic flavor to scenes all companions and advisers get, like "heart" responses to the Orlesian ball and his personal quest or the scene where he prays in the chapel.
I don't personally mind, though. Even though Solas' romance is more... economical, I think it's very well-done. I think Patrick Weekes and the VO and animators and all parties involved were able to make a little go a long way. 
I really don't think so. They could have done more with the NPCs.
Let Cassandra -- after all they never tire of exposing her as emotional, deeply romantic and caring -- ask Lavellan how she's holding up and if she needs somebody to talk.
Let Cullen look at her strangely and ask if she's slept alright... because of... Solas... you know... Maker! He didn't mean to... it... was inappropriate, he is sorry.
Let Blackwall mumble something about how he admires her strength despite adverse fate.
Let Bull comment drily that we cannot sacrifice everything and ignore our duty for feelings and that sometimes things happen as they must.
etc.
I mean, there would have been a roster of possibilities, all in character, and all non-invasive for the PC, who could have reacted in any desired way (angry: "This is none of your business, soldier!", sad: "It just hurts...", appreciative: "Thank you, it's good to have friends.", strong: "I will be fine.", detached: "I think I would have made the same choice later on to be honest. He just ended it before I did." etc.), followed by a standard line by the respective NPC: "Yes, Inquisitor!" or "Alright. But should you need to talk, I'll be here." or even: silence.
Pick any three (angry/sad/detached ; appreciative/angry/strong ; etc.), which is the standard BW procedure. This is basically the same we get for the scene where Solas does actually break up.
I personally don't care about this, I wouldn't need that song and dance. But I simply say it would have been possible to include and I really wouldn't say their hands were tied. Or that they couldn't do right by everyone anyway. There are a ton of good reasons not to address the PCs after-the-breakup state (monetary, if no others), but to excuse it for a lack of options seems rather weak to me.
I agree. Again, I think the lack of companion and protagonist reactions mainly stems from Solas being the most last-minute and resource-starved, not because they can't show any roleplay responses because it might hurt some demanding players' roleplaying sensibilities. (If they expect the responses to always reflect what their individual character is thinking, they need to play tabletop games with friends. Video games can never do take into account every players' possible responses, and people need to accept this.)
I remember seeing an interview by David Gaider about DAI shortly before he left BioWare, where he talked about making the game, some cut Exalted March stuff, some cut ideas for DAI, etc. He mentioned how a lot of fans seem to think the "story" is stronger or somehow easier to write when they have fairly "pre-written" protagonist like Hawke or Shepard, but he mentioned that in a way it's actually a little more freeing to have a "blank slate" protagonist. That is, they're free to write all these weird and fantastical scenarios, then just give the player the option to react to it in a number of ways. They don't have to feel constrained or take into account, "This is how Hawke would react," they can just throw tons of scenarios at the protagonist and then give the player a number of ways to respond.
And that's the kind of roleplaying I personally like better. I don't like the devs telling me, "This is how Hawke thinks/feels," I like the game throwing situations at my character and being given the chance to respond in a number of ways (if just verbally).
And this could have worked for Lavellan regarding the Solas romance. He dumps her out on the blue, the other companions can notice, react, comment on it, ask questions about it, etc. and your character just gets the option to say how they feel on it. Most typical encounters usually just let you choose between "nice, stoic/funny, or prickly" but for bigger moments you usually get, like, six responses--the "thumbs up" icon, the "angry shouting," "teary eyes," "confused," "alarmed," "armor with arms crossed," etc. So, characters react to your relationship, you choose which of the several responses you feel best suits your character. (It's not perfect roleplaying, but if that's what you expected to find in this game, you were probably disappointed long before this point.)
Personally, I think an imperfect selection of responses expressing how my character feels about it is a lot better than NO reactions from characters or chances to respond for the PC at all. (Like accidentally killing your clan and not so much as a "Hey, are you all right?" from any companions or advisers.)
But again, I think it comes down to time and budget constraints in the main game rather than roleplay hogtying. The fact that they added slightly more responses in Trespasser probably shows how they would have done more in the main game if they'd had more time.
But this wasn't her point. She said that he did not seem interested (even if you only consider the physical level) or cooperative.
Whether or not he had a romance in mind at first, the fact remains that he seems to be willing to let any serving girl on top but not the inquisitor. And one could argue (not my reasoned opinion, just pointing it out to be a possibility) that he only acts that way trying to subject her to him because of who she is ("So you're the kingpin here? We'll see about that."), which implies a lack of respect. But he's expressed his respect for her pretty much from the start, which would make him look like a liar/hypocrite (and not only in the comes-with-the-job way).
And: so he wants to relieve her stress but doesn't accept her to set own rules instead of playing by his. If he only meant to serve her, basically seeing it as his duty to assist his superior, he sure as hell should adjust to her and not the other way round.
Thank you, that's all I was trying to say.