I'm more interested in why this gets you so bent out of shape.
After all, spirits aren't an oppressed minority in the real world.
Someone in a game fandom being upset by hostile attitudes and mischaracterizations of a game character? Goodness forbid. A whole bunch of people here and elsewhere in the fandom get "bent out of shape" about a whole bunch of things. And the attitudes and rhetorics I've encountered sometimes are painfully similar to views about some real-world marginalized groups. The whole "there's only one way to have worth and value as a person, and you're not it because you're not like me and don't do what I want you to" that much of it boils down to is exactly the same.
In regards to Solas, he warns you not to get involved with him. It's Lavellan's own fault for pushing him into something he knew would end badly, so trickster or not, he cared enough and I don't see that as selfish.
The "selfish, abusive and controlling" accusations about Solas I mentioned were in regards to Cole (which is totally nonsensical) and not the romance ... but it wouldn't surprise me if some people project their resentment of him dumping them onto his behavior towards everyone else. I do have my issues with him, but his relationship with Cole easily shows the best of him IMO.
I can't comment on the romance since I've no interest in it, but as a brief aside I'd say that saying "I warned you" isn't really enough to shift the blame on the other person.
And he understands Cole because of his relations with spirits, so he wants what he feels is best for him, but Varric too wants what he thinks is best for him. He saw a spirit become human and feels he should continue down that path, and Soals wants him to embrace what he was meant to be. I feel like the Inquisitor was standing between the 2 men staring at her, waiting for her to pick their side like in a sports game. I feel that the choice should have been Cole's, not mine.
Yeah ... they're both "selfish" in the sense that they have a strong preference for one side of Cole and want to preserve that. Though if anything it was Varric who is "worse" about it in my eyes, so it's odd to me that these people think he is Cole's perfect friend and Solas is the badguy.
Since before his personal quest, we can encourage him to be either more spirit or human, by the time the choice is made, Cole should decided based on how you taught him. If he wanted to be more human because you told him to not kill anyone, to speak normally, talk to the girl... then that's why he's human. If he wants to be more spirit-like, it's because you told him to be himself, kill the man out of mercy, make the girl forget... I always felt there had to be a reason you were given the chance to teach him to be more one way or encourage the other, but nothing ever comes of it. You can even encourage him to keep sneaking around to help people, or consider showing himself. Yet in the end it's the Inquisitor that chooses his fate. It feels wrong.
See, I never really saw any of the scenes with him in that way. The "make him more human" thing in his quest struck me as coming completely out of the blue, and I'm admittedly not a big fan of the way the game presents some of its binary choices or of the way the "influence a companion's personality" cases have been handled in the series. (Hello, Leliana-trainwreck.) In this case, there are some valuable messages that Cole can benefit from no matter what path he takes in the end. Approaching people without startling them is one, as is friends having faith in him even when he stumbles instead of just telling him "don't do this, or that, or that".
Though as I think we discussed before, I agree that the way the choice is presented as it is, is really jarring because it's so disrespectful. He's right there, boys, he can hear you, he needs our support and not us fighting over him.
(Regarding the Inquisitor's reaction to the "odd things" he does -- isn't "you're doing good but you don't need to hide" the only feedback you can give him?)
Most of the time, I figure that since he would go back if he could, Cole's stuck as a physical being, unless someone finds a way to undo it. Since no one, including Cole himself, knows how to send him back, I figure Varric can show him how to make the best of what he's got. Solas can go back, anytime he wants, so it's easy for him to offer advice. He can't show Cole how to live in the world he's going to continuously alienate himself from, though.
Cole can return to the Fade on the spirit-path, and mentions it with relief and joy, but still decides to stay. The fact that he has that option is one reason why I prefer this choice. You raise an interesting point, though, and now that I think about it, it is something that should probably have been discussed at some point because "spirit unhappily stuck in the physical world" is a recipe for bad news. Maybe Solas with all his knowledge of spirits realized that Cole is still quite badly hurt from his past and its mistakes (which is pretty damn obvious after all, though the underlying cause i.e. the original Cole's death is not) and needs time and support to heal from it, at which point the ability to return to the Fade if he so desires would hopefully come back to him?