I think we, as server players, have come to expect certain things, and I think that as we, server owners, have come to expect ways to promote our server as best we can.
Most servers have a hard enough time just staying online, let alone field donations to help themselves.
And, V4P gives servers a different alternative.
It gives players a chance to get items, by helping promote (usually freely) a server on a top-site, so that many other hopeful players will join their server, (advertising for the owner), items for the player, and maybe a platinum member for the top site (so they end up getting money.)
I think we've all just settled on a sort of accustomed bribery in it's own ways.