I have no problem with a new protag every game , I play other games where it's the case and it's fine.
The problem with DA is the way the story is structured , Protag A gets involved in some subplot , then this subplot isn't finished or used as a sequel bait then Protag A disappears for some weird reasons and Protag B comes along and it goes on.
I also have no problem with this in theory but again it's the way it's done in DA that just doesn't work so well.
For example in Fallout 3, the pc can find synth in a side quests , they're from the Boston area.Anyway you do the quests , and it's done .
There's nothing personal here for the fallout 3 pc , a normal side quest like any others but it did open up a sub plot for Fallout 4 for a new pc.
Now in DA you end up with some wardens having a God child with a witch , and the third pc has to deal with this sub plot because well it's there , and the parent is busy in some far away land just because.
Of course I do understand why it's done this way , it would be a mess to bring back the warden .
Then we have Hawke who make a cameo in DAI just to say "Cory is mine" but then he turns around and goes "K thanks , bye, I have something to do somewhere far away!" (sounds familliar?)
and finally the Inquisitor "I will stop you Solas!" and I'm waiting for the "But I can't because I have something to do somewhere far away too!"
Anyway my point is if they keep on with one pc per game , for the love of everything ...solves every personal plots as soon as possible .
Open up new sub plot with non personal stuff when the pc doesn't care much and has little reason to get involved in this in the future , like the Inqui and the Titans.