A huge issue with the DragonAge game was that they spent a massive amount of development time trying to turn it into a 'live service' game, then pivoted to a classical single-player experience. Putting the sociopolitical messaging aside (and whether it was 'real' or 'perceived'), a development cycle that completely pivots that sort of underlying, fundamental paradigm shift is going to undo a massive amount of development work...and EA still found it necessary to have the devs do a bunch of last minute 'crunch' and 'ship now patch later'...which meant that the early reviews reflected some of the rough edges, and then the sociopolitical messaging accusations at the height of "anti-woke" sentiment was just the icing on the cake...and thus, the flop.
You are half right with "development hell" being a problem, Inquistion came out in 2014 and it took a decade for the sequel to come out. Now I loved Origins, enjoyed Awakening, tolerated II, and enjoyed Inquistion again. However 10 years is a long time, and Veilguard looked contra to everything the previous Dragon Age titles stood for. The characters were annoying, the combat was very dumbed down, there seemed to be no meaningful choices or even the appearance of important choices, other than ignore your companions and they all die in the end(spoiler). As you mentioned BG3 came out and really set the bar for what a cRPG could be, so Veilguard looks even worse in comparison. The gender politics being shoe-horned in was just the chipotle aioli on the shit sandwich that was DA:Veilguard. Hell 5 years ago when it changed from kill the dread wolf in Tevinter to whatever this was(I guess they wanted to reset the world and start over again, only reason to destroy the country you spent all of Origins trying to save[again, spoiler]). Hell, I'm surprised this game didn't become a card draft auto-battler or a MOBA.