I'm not really part of the sol/avellan fandom (or not a loud fan), but me wanting the veil to come down has nothing to do with "believing it's best for Solas' character" and is 100% related to what I think would be interesting for Thedas and its characters, narrative-wise. (And I am only speaking for myself here.)
And what I think would be interesting for Thedas: overturning the current status quo; actually tackling the problems with much of Thedas' view towards magic, mages and spirits at the source; exploring what "one day all the magic will come back" could mean; having the WORLD realise/deal with the truth about the veil and its implications for society. And maybe dealing with the fact the veil was deteriorating; it was naturally going to come down anyway and that likely may come to pass post-DATV. (Say maybe 10,000 years into Thedas' future? Ignoring the endings where Solas is trapped against his will, may escape with the lyrium dagger and do who knows what concerning the veil.)
Also I very much wanted to see some change, some progress, some strides being made towards improving the elves' current disenfranchised status. Which you know... would've been more plausible and likely if the underlying solution to DATV wasn't keeping the macro framework of today's Thedas intact!
I'm 100% sure other, more eloquent fans have put forward this perspective already. I wanted to vent in response to what I just read ┐(´ー`)┌