Agreed. And it's not like the old world wasn't just as corrupted. Else Fen'Harel wouldn't exist as Solas would never have rebelled. So, bringing down the veil won't bring about Utopia, even in the long term once things settle down. As usual when there is a void, something will take its place. In this, Sera has more wisdom than Solas. From their conversation about the Red Jennies, when Solas asks her why she doesn't work on overthrowing the nobles and she answer with "What's the point? Some other corrupted people will only take their place" or something to that effect.
But, I doubt Solas is even thinking this far. All he sees is his mistake (the veil) and that it needs to be undone. As I'm unsure he even expect to live past the lifting of it, he's probably going "Eh, once my mistake is fixed, whoever is left will sort themselves out. I can't choose for them." Heck, I had the same reaction at the end of Trespasser when I realized Vivienne was resurrecting the circles despite my freeing the mages. "Eh, at this point, I can't choose the mages' future for them. They need to settle this for themselves."
Do I even make sense?
Perfect sense. People have to want change or they tend to just revert back to the way it was before. That was the whole lesson of DA2, I thought, and why Anders was so frustrated and forced the war. Because it wasn't really just the templars, as bad as they were, it was the mages too, remember..."they do it with our blessing". Does that mean no one should ever try to change anything ever? No. But there are a lot of people on both ends on the extreme, either trying to preserve a status quo at all costs, or chasing a uptopia that doesn't exist. Ok so Viv can have her circles then, I just don't see why everyone else has to be forced into it. Fiona can have her college too, why not? But watch, they will war amongst themselves over which system should be, as is implied in the epilogue. Gah you can really feel IQ's frustrated rants in Trespasser about things staying fixed