The bit I read of WoT Vol. 2 emphasizes paranoia that Leliana was becoming better than she was as one of the primary reasons for Marjolaine's betrayal, so I guess it's possible she was different at one point...but she screwed her over so very casually, so I'd find it hard to believe she was ever more than the manipulator. I'm still of the opinion that Marjolaine was playing her like a fiddle since day one, and sad as it is, those good times were just part of that. A cruel lie.
Very interesting idea. Has Vol.2 been released yet? I was curious if there was anything good about Merrill in it, myself.
I wonder if Bioware writers sit around and sometimes mutter 'that bloody Warden! They just won't let him go!' 
Agreed. I mean, the heroes of Dragon Age have been the Warden (wow), the Champion (cool) and the Inquisitor (Indifferent). Is it any wonder people like the Warden best? *tongue in cheek*
Exactly. If the writers don't want people asking for the Warden back, well, then they shouldn't have written him or her to be so awesome and engaging. They have no one to blame but themselves, really. That's also pretty much the same metric I use as well; the Warden is fantastic, Hawke is pretty solid (and deserving of a better game than she got), and the Inquisitor is pretty meh.
Dunno about Morrigan, but I set my Warden to dead in the Keep once for scientific purposes, and the way Leliana spoke of her was enough to get me to nope out of that playthrough for good. Hell, I looked it up, even Leliana's dialogue if the deceased Warden was just her friend rather than her lover is pretty damned heartbreaking too. "The world seemed so much emptier after that...it still does."
Yeah, inflicting an Ultimate Sacrifice Warden on Leliana is just too painful. That was my Warden's motivation for doing the whole Dark Ritual in the first place; after a lifetime of being selfless and acting on behalf of the helpless, living to make Leliana happy was probably the only time he truly let his own desires override his sense of duty and honour.