No offence but your argument is really narrow minded. How do you think HoF himself came to be or Inquisitor for that matter? They have different races different origin but still all this varieties people together make these PCs. Now what you basically saying is: No, no creating another PC that can be HoF won't do because there will be too many differences! - and fully ignoring that both HoF and Inquisitor were created that way. So HoF who is HN, or DE, or CE, or DN, or CD are fine with you but NewPC who HoF, or Something another, or Something another, or Something another is not - cause it is too hard to realise.*facepalm* At least this way reuse of old companions has more meaning. Funny thing that people who you oppose want consequences for their choices where you are saing: no, no - about game series that builded on choices and consequences and Game Studio who specialize on on choices and consequences. Dragon age is RPG series about choices and consequences if you don't want deal with them go play Skyrim. 
Here's the problem with your scenario, and I'm going to try to keep this as simple as possible:
With the Warden, we had no expectations of who that character was prior to playing it to the end. However, now that it's played out to the end, everyone has a preconceived notion of who that character is if it's appearing in another game. The same applies to Hawke and the Inquisitor. There's been backlash about Hawke's appearance in DA I, because "It wasn't my Hawke". Ironically, Hawke caught tons of flak, up until Inquisition released, then, all of a sudden, Hawke was akin to the second coming. For all the "the Inquisitor was too bland" posts peppered throughout these forums, there's at least a half dozen threads going already that the Inquisitor should be the protag of the next game.
So you see, despite your bitterness, or whatever, I am actually looking at choices. I'm looking specifically at BioWare's choices, to go with a different protag every game, and then reading here all about people that sincerely believe that the only choices that matter are their own. As I mentioned earlier, which "HoF survives" scenario is the "right" one? Yours, Player X, Y or Z? Because the DR isn't the only possibility, and you can bet, the people that told Morrigan to take a long walk on a short pier, and then let Loghain redeem himself are going to be irate if Alistair took the killing blow. If you think I'm making this **** up, take a look at the "So the OGB was nothing" thread. All kinds of people there that think their personal canon should be canon for the series.
...and we need one. We need to run with BioWare's canon for the series, a female DE who made the US to end the 5th blight. No more hassle about HoF returning, they're quite dead. No more hassle about the OGB, it doesn't exist. They attempted to wrap up Hawke's story in the slides at the end of Tresspasser, and people aren't happy. Why? Because their personal ending for Hawke wasn't the one they used. That's the problem with choices, you get to a point where there's so many of them that you can't do anything with them.
TL;DR? A new protagonist has no previous history with the players, and so, the millions of ways that a specific character can vary from another doesn't have to be accounted for. There's a difference between "I'm an Elf" and "I'm a HN" and "I'm Sara Cousland".