Solas is apparently being forced on us, anyway. I would have preferred that the foundation of that be more sold.
And that's really part of my problem. It's over done, cliche, and I have no interest in seeing it again.
Not to mention those are some qualified examples. They went out of their way to establish why the wardens are the only ones who can defeat the Arch demon and it wasn't due to personal grudge. And in the end, you can have Alistair or Loghain do it instead. Shepard was the only one who did draw the attention of the Reapers, but he never declared that he was the only one allowed to save the galaxy from them. If anyone else did it, Shepard would have been fine with that. And I don't like Harry Potter, so that isn't an argument to convince me this is a good idea.
And I can't help but think about it from an outsider's perspective - which I think is a testament to how much they've failed to get me invested in the story. I don't think about it from my Inquisitor's perspective of "I have to be the one to stop Solas!" I think about it from a hypothetical new protagonists, "Why the hell should I let that guy deal with this? For all I know, he wants to help Solas. I'm not leaving my fate in his hands, I'm going to do something about it!"
History isn't shaped by any one individual, it's shaped by multitudes of great people. And rarely in history does one actually get to defeat one's arch rival personally. Someone else always blindsides them. That's a story I'd be much more interested in seeing than another "I'm the only one allowed to defeat you".
Thing is though, where they failed for you, they resoundingly succeeded with me. If the Inquisitor isn't the one to go after Solas, I will be gutted because they have very much created a relationship there that resonates with me far, far beyond 'here's a bad guy, go and kill him'. That they failed for you is a shame, but your solution (entirely new protag, no Inquisitor beyond a little cameo) is the one that I would consider the failure.
Yes, they are qualified examples - but not isolated ones. A great, great many video games feature protags who, for one reason or another, are the only ones who can do what they do. The 'any old joe' idea is nice in theory but risks being anti-climactic and, well, boring, in practice. That you don't like Harry Potter and won't play TW3 doesn't make including those things in my arguments less sensible.
And while the whole of history isn't shaped by one individual of course, important moments in history absolutely are. There's a reason why there are entire eras and movements in history named after people - 'Napoleonic era', 'Trotskyism', 'Thatcher's Britain' - phrases used commonly enough to stand as testament to how important the actions of individuals can actually be, for good or ill.
And really? I'd have been horribly ticked off in Origins if I'd played a Cousland whose revenge against Howe was taken away from me by random guy who had nothing to do with what happened to my family. There's a reason we get to face down our nemeses in popular media - because it's satisfying, in a way that some bloke doing it because reasons, isn't. And as a player of Shepard, if another soldier had turned up and defeated the Reapers while I was faffing around on the Citadel, I would have been very unhappy, to say the least.
Part of the reason I love the Solas/Inquisitor stuff is that it's not (or doesn't have to be) quite so simple as 'I'm the only one allowed to defeat' you, but also 'I'm the only one who can possibly save you' - which is, in itself, an interesting twist on the traditional dynamic, for me.
Edit: And, like Abyss, I'd love dual protags, which wouldn't negate what you want to see anyway.