Good points overall Chris. Two things: 1) In some ways our cultures are 'wussifying' (nice term) but in some ways it's actually become more violent, or at least we have become more desensitized to violence. It's arguable that to the layman, MMA is more violent than boxing, yet it's very popular. 2) I personally don't believe MMA or any other such sport is to blame for boxing's decline. All MMA did was take advantage when boxing was busy shooting itself in the foot. The big Philly gyms and fight arenas were closing down before MMA even arrived. Same in Miami etc. Honestly, the alphabet groups, lack of core marketing and losing the mainstream sports fan would be my pick.
joe calzaghe is probably the greatest smw of all time because there isn't really any other fighter who even lays claim to the super middlweight division, it was virtually a dead weightclass stuck between middle and light heavy, it really has no history and is pretty much a new weight class
When it started to not be in the mainstream. Namely Television. When is the last time A good Boxing match was aired on network television on a Saturday or Sunday afternoon?? Some of those matches we used to watch on ABC,NBC or CBS. Would be on Pay per View right now.