It's an interesting exercise to square this approach with the promise at the heart of free software - freedom. We let people sell our software for a profit; we're a billion-dollar industry now. (Red Hat alone is worth $1bn.) That's before we start counting the money made by the businesses whose servers rely on us. But a developer advertising for €25 per month in donations? They must be banned!
We need those buttons - how else should I deduct reputation points from those who want us to pay a tithe to a third party? :)