Look, thing is the following: Some huge servers (such as empireminecraft, obisiandcraft and legendarycraft) are just business, registered as companies or at least with a social reason somwhere in the world.
If you stop to think, that's the reason why they have to put "buy now, purchase now" or something like that instead of "donate" (It's a policy of PayPal to do it that way)
Obviously they don't tell anyone about that, reason is simple: They want to do profit out of it. Server costs are WAY lower than server "donations" and that's where they take the money from.

It's nice that you say stuff like "I feel it wouldn't be right to take that money and go to the movies."
Well, just FYI, this people don't go to the movies with that money, they live with it! Obviously they have other works and stuff like that, but they take some real money out of it.

Just make a great server, you will see people will donate, and if you don't get enough donations, start looking for other ways to make your server better.

as long as you make it clear to the donaters what there donating for its all good

It doesnt matter how many donors I get, I can always buy some things for the server

well maybe if u find away to advert places then you could get more donors