It seems like a lot of smart people are involved with bitcoins. People that would also be likely to contribute to wikimedia, so these two projects would go nicely hand in hand. It's not so much that bitcoin have more to gain at this point than there is to gain from wikipedia. All it would take for wikipedia would be to ask bitpay to set up a payment solution for them, or some other payment provider, so they didn't even need to touch btc if they didn't want to.

The effort involved with accepting bitcoin is about as difficult as setting up a jar in a bar.