R said in the Game Informer preview in 2012 that Trevor was a different kind of criminal than they are used to having. They wanted to show a different kind of crime and there are many criminals out there like him. They want the freedom of that lifestyle instead of it being just material gain. I am glad they did something different instead of another gangbanger or mobster.
Well in my opinion, it did not work. Oooh wow, Trevor is such a badass, he's so crazy, wild, extremely violent and destructive. Ok great, what next ? Oh wait, and just for added fun, he dresses up in women's clothes and underwear when drunk, and he possibly likes to have sex or get intimate with other men too. Nah, not sold on any of it, and I'm nowhere near impressed. Trevor and his story was just a load of bullsh*t. Would have been the perfect antagonist or NPC.
Trevor was just a waste of protagonist space.