Currently for banning that's just the standard of PC gaming amongst privately run servers. It's all up to the admin. On the Crytek funded servers their standard is obvious, no hacking. They enforce that by issuing origin bans. About your idea on the votekicks, pretty good thinking. But I think along with the votekick system that would get abused also. People call other players hackers all the time and they are entirely wrong. You can always enter in the chat what the reason is despite others not giving the same courtesy. The new system that shows the person who initiated the vote kicks is so much better. Also your idea of having a choice for reason of vote kicking would probably require implementing a new user interface for it, something that I understand is very difficult to do later in a development cycle.
Either way that's good outside the box thinking. (no pun intended).