This! I'm replaying my Lavellan PT again and I'm still finding it impossible for me to fully like Sera when I play a Dalish elf.
(I love a lot of "elfy" things as well) With a Trevelyan, I'm fine with her (I even got the cookies-on-the-rooftop scene) but as a Lavellan? Pffft! I really wanted to strangle her after the Temple of Mythal (and after she laughed at my face about the removal of my vallaslin). Sorry, Sera fans, I can't help the way I feel about her.
As much as I love Solas, yes, this part of him is rather irritating.
I wanted to say more about this, but I think other people have already explained it better than I ever could.
You don't have to tell me twice. 
My beau has only played DAI as non-elves, so Sera is one of his favorite companions. He could not for the life of him understand why I found her anti-"elfy" comments so abhorrent. He felt she's not that interested in elfy things but doesn't hate it, and I could tell he felt I was being the racist I was accusing Sera of being since I didn't accept that she's just not that into elves. I finally had to show him some Youtube videos of Sera saying insensitive things to a Dalish Inquisitor (particularly the post-Temple of Mythal ultimatum to denounce your faith or get dumped by her) before he understood and backed off.
I'm doing a Sera-romancing Adaar at the moment and, wow, she's much easier to befriend as a non-elf. Flirting with her and asking her about herself gives much higher approval, and you don't lose approval for asking about elfy-stuff. It's giving me a different take on her character.
Sera is interesting as she's the only elven companion who doesn't see herself as elven (Velanna, Merrill and Ariane were all Dalish, Fenris identified as a city elf if his banter with Merrill is to be believed and Zev may not see himself as Dalish or a city elf but he clearly identifies with elves and see them as his people). So she really isn't typical. I just wish her romance with a Dalish didn't end with 'me or your faith' and you could get her to accept some of who you are. It feels like Lavellan has to do everything to accommodate Sera and her views.
Yeah...
Like I said above, my boyfriend and I had vastly different reactions to Sera's character, since his first playthrough was as a Qunari (then Dwarf) while mine was a Dalish. On the one hand, it's great story-telling and characterization since Sera's strong views really do come across differently for protagonists of different races. If you aren't an elf, her dislike of elves isn't so in-your-face. If you are, her prejudice hits you full in the face every time since it's your face she's hitting and not the others'. On the other hand... it can make her not-so-endearing to elf and Dalish-lovers. (For example, for all her talk of disliking human nobles, she accepts a Trevelyan way more easily and quickly than a Dalish Inquisitor. I guess she really does hate her own kind that much.)
Solas may not agree with the Dalish but keeping the vallislin doesn't change his feelings towards his lover.
Agreed to that.
Removing the vallaslin is a very popular choice, and a lot of people comment how they love "magic hands" Solas.
While I can see the appeal, to me nothing compares to how he says, "You are perfect exactly as you are" and means it.
Especially poignant since Solas has made it very clear he doesn't like the Dalish at the best of times, can't stand slavery or bondage of any kind, and likely cringes every time he sees Dalish wearing their slave markings with pride. A Lavellan he falls in love with who potentially subscribes to the Dalish culture would also be hard to look at, since every time he looks at her face he's reminded of "what those cruel marks represent." Yet, if she chooses to keep it, he's not only able to "see past" the marks and what they represent, but fully and completely accept them as part of who she is. He accepts her for who she is, vallaslin and all. 
I just really wish that there was more elfy dialogue between Lavellan and Solas. If Lavellan had the option to jump into banters between the two of them and take one side over the other, that would be interesting.
That got rather rambly. Sorry.
Oh, not to worry. You're talking to the queen of rambling.
And I agree, they would have been so interesting to jump into the middle of. As it is, the only bit of Sera and Solas "elfy dialogue" we can jump in is the romance dialogue, when Sera says, "Come on! Drop 'em and rebuild the empire!" Eh, better than nothing.
For the rest, I guess that's what headcanon is for. 