I know Kieran would be older, but at least an appearance by him would have been good, but where exactly is he? Mythal/Flemeth did take him somewhere. Is she truly dead, does she semi live in Kieran now? So many questions left unanswered.
I agree with others that more of the previous choices should have been included in Veilguard, or affect it in some way. They could have easily had a system in place to transfer the main choices from the Keep to a new one which Veilguard could use. I think that was just laziness on the part of the devs to be honest.
Zevran for instance would have been a good side quest NPC, especially regarding the Crows.
Anders if still alive would have been good as a sub plot for the Wardens.
And as someone else said Casandra would have been great too, one of the choices you could send over was of course giving the Inquisition to the Chantry which resulted in a few words in a speech by the Inquisitor in Dock Town's bar. There was no real difference between the disbandment or ownership of the Inquisition.
It's as if they just wanted to take everything that came before and wipe the Lore clean, we had no idea about the blight's origins other than it was the result of Tevinter mages in previous games, now it's gone down a totally new path.. I get it makes a bit of sense, but it makes it look like they are now kittens for unleashing the blight from the veil.
It needed more ties to previous games...
Sten - would have been good also in the game, helping out Taash
Blackwall - wasn't he sent to Weisshaupt as a choice? He could have made an appearance too.
Fenris - on a crusade still, he is against Tevinter mages after all.
Sera - although immortalised with a ring, bees 'innit. Would have been a fun NPC not involved with quests just for the banter.
Anyways enough of my /rant lol