I love Lars Sullivan because I love Big Sweaty Men
Ok, seriously though, there is SUCH an upside to a guy like Lars. He reminds me of the "final Boss" in an SNES fighter game (which makes him the perfect heel). I have always been a component of simple characters in wrestling. Heavy Machinery are big guys who like to eat and lift weights, Street Profits are guys who love to party and have a good time, Lars is an angry man who wants to hurt people. Not everybody needs an elaborate back story or complex gimmick, sometimes less is more effective.