Ha, this is such a widely debated topic, it's great!
I would have to jump on the PRO AC PC bandwagon, mostly because of the symbol. I only figure that since to have a symbol and not a character is out of the smash norm. We haven't seen a cahracterless symbol yet, so it would be a change that most figure wouldn't really happen. I don't mid either way, but I reckon it's more likely than unlikely. It's a much better argument than the logic one. People argue logic in this game, it's so stupid and funny. You want logic, then I want Link to cut people in half with his sword and for the opponent not to come back...Wouldn't make for the greatest game, would it? (actually, it would be pretty cool, haha).
Oh, and the whole needing a symbol to show what game it is from otherwise it is a Smash original argument, it has upsides, but then again, people could say (and probably have, I haven't read it) that all the assist trophies that don't have their own symbols are being paraded as smash originals then. I mean, it wouldn't be hard to make symbols for everything, they aren't particularly big or technical or detailed.
Yeah, but I don't really mind. I think the main reason I want one in is because of a guy from another forum, he played a high and mighty routine, saying he knew there would be NO AC character playable. Just want one in so to discredit him, knock him down a peg or two. Heh, ah immaturity is KING!