Well, that's where we differ, I suppose. I'd rather have a good story than a profound choice in who gets what destiny. I even get frustrated when characters [Like Wyll] leave it all up to you. Just, make your own damn choices, dammit.
And plot holes aside - I think her story works well in that, she comes to terms with her impending death. Choosing to 'live free or die hard' is rather powerful - something I personally struggle with, living on borrowed time as it is.
But there is very little in terms of helping her get there, either. And, well, dying - especially choosing to do so - is an extremely lonely endeavour. Loneliness being her biggest gripe with her time in the hells, I rather find *that* aspect lacking. Sure, you can take her to dinner if you romance her, but as just a friend there is nothing there. Compare that to all the obnoxious dialogue you get with Mizora - on a normal playthrough and not skipping through that dialogue, I think you're looking at half an hour's worth - if not more of JSUT Mizora. And she's not even your companion or friend, or anything.