Re: Why are all the best gimmicks midcard gimmicks?
With the Kane example, I'd argue that he came from an 'earlier' era, where gimmicks could still be pushed right into the main event. You had guys like The Undertaker up there, and before him someone like Ultimate Warrior. As we moved more and more towards a 'reality' direction, so too did the characters up top. It became guys with regular names (the John Cenas, the Randy Ortons) instead of guys with masks and superpowers.
Credit to the incomparable CHAMPviaDQ.