there should be some drewbacks for evilts... as someone said, like wiping out a complete planets population... just for the fun of the leader, at least he/she is evil.... or in a sudden attack of agression, the research progress would go some % down.
the diplomacy bonus is nowthing worth, given the proper technologies, an evil race is as good at diplomacy, heck, in one game I was pure evil and have had 2 alliances with pure good civs, which lasted longer then anything else I ever had.
I wish events could be defined that way, alas its not possible, there is no if variable in check for the alignment in events right now