The thing is - for those who have their HOF alive, they are going to want the option to recreate their character. Then there is the voice - not everyone wants their warden talking, then there is the weapons. My Hawke was daggers in II yet she was archery in Inquisition (Despite the act I never used a bow or put any points into archery).
Then of course - there are those who have different Wardens.
My City Elf disappeared, wanting to have nothing to do with the Grey Wardens so I certainly don't want to see her as a Warden or working with the Wardens because she hated them.
My Human Noble married Alistair and is his Queen so I can accept her being at his side if he was to make an appearance in a future game but not without him. There is no reason for her to be away from him if she has found the cure (including Grey Wardens because she became a Queen and made Alistair a King precisely the reason to keep them away from the Grey Warden - Awakening screwed that up which is why I never play it with my Cousland).
My Mage Elf romanced Leliana so I wouldn't be surprised to have her at Leliana's side in a future game (still no ties to Grey Wardens because she ran as fast as she could to get away from them).
My Human Noble, who romanced Morrigan, would have an excuse not to be at Morrigan's side, he could be looking after their son if Morrigan shows up in a future game or is happily retired (and hopefully having more children with Morrigan).
Plus - not everyone was happy with Hawke in Inquisition because they weren't their character. My Hawke were usually a mixture of personalities so being constricted to one actually threw her off balance.
I think - if I can't play as my HOF, I don't want them in a future game because they won't be my character, they will be Bioware's and I don't trust them with our HOF after Hawke.