Donors keep the servers running - donors are the only reason these servers are free to play...people would be forced to pay if it wasn't set up this way.
Donors have to get some privilege, otherwise there is no incentive to donate and not enough money will be coming in to keep the servers up - the best way to do this is to allow kicking and priority access, since in game advantages like starting with a sword would be extremely unfair and even more frustrating than being kicked.
Donors will always be able to kick people, the system won't be changing - a tip to you to prevent being kicked is to join the servers as soon as possible - look for a server in deathmatch and wait for it to go down, and just as it comes back up, join right away. Unless there is 12+ donors (unlikely) in your lobby, then this plan should be foolproof provided you have at least a decent internet connection. (Donors kick the last non-donor spectator that joined.)
Your only other choice would be to join the donors and kick people the same way - even if you don't like it, a post like this won't stop the donors and won't solve anything. Trust me, while it is frustrating to be kicked by a donor, it's not like that person cannot join another server with said "fool proof" plan and not get kicked. My first 200 victories I earned without donor or mod joining priority. There is a way to avoid being kicked, the people being kicked just need to learn how to avoid it - that's up to them if they want to figure out the best way. (And trust me - those with a connection bad enough to not join right away to prevent being kicked likely lose a lot to lag, too - that's not something we can really control.)