It seems to me that people are conflating "identity" with "I like". A fighter has a very clear identity - they're the martial weapon expert who can go toe-to-toe with the bad guys without necessarily relying on supernatural abilities. To me, that's pretty clear. Same with wizards, yes they may be a boring concept to some people (I think the subclasses give them their identity) but they are the iconic study spells and cast away class that relies almost solely on their spells to make a contribution.