Hasn't Solas suffered enough?
It bothers me more and more that all the Veilguard endings (except sort of Solavellan) are predicated on the idea that Solas must be punished. Partly because I'm not a fan of retributive justice so this just seems philosophically misguided to me. But also - OK, some people just hate him and want him to suffer. Still, the game put a lot of effort into showing his long history of grief, loneliness and guilt; he's been suffering for thousands of years already. What does more suffering achieve? Exactly how much pain will be enough for you?
Naturally I dislike the fight and trick endings, and find them gratuitously vindictive. But ultimately even the Atonement ending assumes that Solas has to be punished. There's no narrative reason at all why he has to go back to the Fade prison in that ending, but he's made to go there anyway because I guess the writers are just stuck in a retribution mindset. Not only that, it's a particularly cruel choice of punishment: sending him to be alone forever, after previously establishing that his greatest fear is dying alone.
Indeed, the only way to get an ending which offers hope for Solas to find happiness is the Solavellan ending. And while I love that it exists, what about everyone who didn't romance him? Surely some of them might also be against punishment for the sake of punishment, and might want another way?
It also seems really narratively unsatisfying. We've been told often that one of Solas' biggest flaws is his insistence on working alone and not trusting people. Veilguard repeatedly lectures us on how it's morally good to work with a 'team.' So how does it make sense that the resolution to Solas' story is to make him be alone forever? Even if you want him to be punished, wouldn't it make more narrative sense for that punishment to involve working with people and putting his skills to the service of a community? Wouldn't some kind of learning and growth be more satisfying than just sending him back for more of the same pain?
And look, I know it's been said that Veilguard critics focus too much on Solas. But this doesn't just happen because some people like Solas too much. People focus on Solas because the game focuses on him. Nearly ten years ago they set up a premise which was all about him; he's the central figure of both the start and the end of Veilguard, we live in his home, we examine his memories in detail, he's part of nearly all the main events of the story. If you're going to focus that much on one character, people are going to judge the game by how well that central plot thread gets resolved, and this way of ending things just is not a good resolution because it's a bad fit for the themes of community and healing that the game itself is trying so hard to promote.
"Partly because I'm not a fan of retributive justice so this just seems philosophically misguided to me."
THIS. So much this. But sadly, society as a whole has never outgrown the concept.