There is something .... Different about the minecraft modding scene compared to others is there not.
I would say its about money but some mod makers don't make money (some do) its more about power and ego.
If you put a line of code into your mod that says you cant use this mod under these conditions(mods installed, character username, style of perfume your wearing) in some of the games i have played modded in the past you would have been driven out by the community.
Nowadays you can get away with anything you want apparently.