I wouldn't mind at all if they had some special challenge modes added in. My younger brother LOVES replaying games on harder settings. For him playing video games isn't just about having a pleasant experience, it's about totally and completely mastering the game set before him. He's not satisfied until he feels he's conquered a game. He's on his third playthrough of Dark Souls setting his own restrictions like time limits to beat an area and as different classes, and who knows how many hours he's logged into Binding of Isaac unlocking everything. And I mean EVERYTHING. There are completionists, and then there's my brother. Adding challenge modes would be a great a way to keep people who live for the torture playing Y-L for a loooooong time.
I'm a fan of the limited lives mode idea, or at least an achievement for not dying or dying fewer than X-number of times, too.
you kuh lady