"The freedom to take stuff"
"The freedom to have stuff taken from you"
Its a matter of whether a given developer has ideological problems with someone using their freely distributed solution to create a new solution that is not free (and thus locking away any potential improvements that tree of development and use might ever produce from every other development and use tree) and thus working to ensure that any future development/use patterns of the solution will also be free to be adopted, improved, etc (the GPL) OR if they're just glad that what they believe is a good solution gets used as widely as possible.
I see merits in both attitudes, and potential for abuse in both. As a person of a rather puritanical bent though, I tend to get itchy about people reaping rewards they didn't earn or contribute to (I don't have much fun in Vegas obviously) and thus tend to favor the GPL outlook.
Frankly though, I just want to beat the ideologues of both camps with clawhammers. In a purely metaphorical sense, of course.