There are several great organizations that have no way to make money, so they rely on donations. Wikipedia isn't in that situation. They could sell ads that were clearly marked as such. A simple small text ad on each page would give them more money than they would ever need.

They're costs seem to be low enough and the value of ad space is high enough that they wouldn't have to put up with anyone trying to extort them or take away there independence.

If they are worried that the surplus of money would corrupt their organization, then they can give the surplus away or just limit the number of ads they sell (but maybe hire a couple more devs first).

That is why I will not donate.