actually putting money into a P2P game does what you said "money goes to improving the servers directly."
it's with that money that P2P games constantly release new content, fix issues that pop up and have top notch customer service.
granted you're a student... I still don't understand the logic of 15 dollars being a lot though unless you're scared 2 work... minimum wage is what... 8 dollars there or something? christ even if it was an even 5 it's like 2 hours a month of work 2 support a P2P and get about 10 times more than you would out of a F2p.
if F2P games were on the same level as P2P I could kinda understand... but they aren't even remotely close... there's a reason people pay into P2P MMO's... and it's not cause they like throwing money out the window... it's cause they want a solid gaming experience which you will only get with a P2P MMORPG