I've never bought the idea that men need men leading characters to identify with for a movie to be successful. If you want to sell a man a magazine put a woman on the cover. If you want to sell a woman a magazine put a woman on the cover. Now this gets into all kinds of sticky issues with objectification and male fantasy, but at least proves the starting point.

Also, Wolverine has a much longer track record than alternate spider heroes. I'm not sure I would have seen this Deadpool in the theater if it weren't for the presence of Wolverine.