Ugh, I don't mean to be rude, but may I PLEASE point out the fact that every character had THREE different modes of unlocks? Don't you think this was there for a reason? Think about it.
SSE Method: You had the RPG/Sidestroller fans who enjoys the casual romp and exploration of meeting people as they fight towards a common goal or similar interests. The way you have people cutting in and out of the battle is what you'd expect. There's no instant gratification as that's not the point of an RPG.
Single Player/Collectors: These guys don't have the time for a big adventure, or maybe they just want a challenge that's not a straight up brawl against computer for lack of friends. You've got the various quickies of classic, Events, and other things to indulge yourselves with, and a chance at discovering new characters to unlock.
Fight X-Number of Battles: This is the grind-method, but honestly, when you have a large number of friends. The numbers are going to rack up like no one's business rather than seen like a dull way of doing things.
All in all, I thought Sakurai had the right of it in how he did things, it's just today's generation has had things handed to them on a silver platter and things have been dumbed down so they don't get too frustrated rather than appreciating the challenge and success of a hard-won fight. It's all about instant gratification these days and not wanting to stress their brain pans, sad to say. Admittedly, I'm guilty of this at times, but that's the point of entertainment, PLAYING the blasted games rather than having it played for you. When you're resorting to tactics like what Amphoros above me is doing... you probably have no business buying this kind of game if you knew ahead of time what you were getting into. We should appreciate the effort put into these games and ask why they chose this instead of complaining without all the facts. Admittedly, WarioFan does have a point about some of the chosen unlock methods. That was a bit out there.
Edit: Whoops. Yeah, forgot about Wolf, Toon Link, and Jigglypuff's unlock. That was the odd one and probably falls under the "What were you thinking?" category along with Mewtwo's 20 hours of gameplay unlock.