Daniel Jalkut posts on the disadvantages of the GPL. He argues that the viral nature of the GPL is off-putting to some developers who may otherwise contribute to a project that is licensed under a BSD-like license. That’s completely true. But it’s also beside the point. The GPL is explicitly and intentionally political. The goal is to force more software into the open source world.
The political nature of the license is certainly going to alienate some people, but any true advocate of the GPL will be completely OK with that. Knowingly choosing the GPL means you’re willing to take the “bad” with the good. The problem Jalkut describes has more to do with people who mistakenly equate “open source” with “GPL”.
Developers need to study the licenses before they choose one to release their software under. I’m not sure the GPL is the ideal license for WordPress, but clearly it hasn’t hindered its success. Complaining about the GPL’s encumbrances is sort of like complaining about the fact that when you buy Sierra Club merchandise, part of the money funds environmental causes. That’s the whole point.