Ok, theres two sides to Admin's in my view.
First off the Admin Side:
1. It's thier server, therefore they make the rules.
2. Anyone who has done any kind of administration for a while gets a short fuse after so long of dealing with the persistent droves of idiots that pervade the internet.
And Secondly, The Player Side:
1. Most players feel they have the right to speak as they choose.
2. Players also feel they have a need to a fair game.
3. Ego alone makes many players fail to see when they are doing something to upset an administrator.
I know this is short and far from complete, but its just my views from the top of my head. Bottom line, if you dont get along with the admin, dont play on thier server, if enough people get fed up with a certain admin, the server they administrate will either die off, or end up being a semi-private server where the admin and friends of the admin will play and the problem will be solved.
Also of note, THIS IS THE INTERNET, it's not fair.