The "donation" methode is more or less an abuse, it is only used due to law issues with blizzard that you can run a server without charging someone. I can understand that some try to get donations since servers cost a lot of money....but lots of the big servers use that as an income and business methode.
The definiton of donation is the following:
A
donation is a gift given by physical or legal persons, typically for
charitable purposes and/or to benefit a cause.
Donations are gifts given without return consideration. This lack of return
consideration means that, in
common law, an agreement to make a donation is an "imperfect contract void for want of consideration.
I dont know exactly the regulations here with blizzard but I wonder that such big servers get not shut down by blizzard, on the other hand we as players profit from it aswell of course since we can play on such servers. But the whole donation thing refering blizzard licence is a sign with 3 questionmarks for me.