define "a while"?
Joker has plenty of layers to him. Just all depends on who writes him.
To say he's "just a psycho" (do you mean psychopathic or psychotic?), just sells yourself short on understanding psyches, illness/disorders, etc. I presume you meant "psychotic", but no simple psychotic could ever be a criminal mastermind, really. One could be an a-hole psychopath, but still have plenty of layers to them. Plenty of psychopaths are actually quite complex. Especially self-aware ones like Joker can potentially be viewed as.