I think the reason I don't like the GPL is that it is aggressively pessimistic. If you release your code under MIT or BSD and _ask_ people to contribute back if

I think the reason I don't like the GPL is that it is aggressively pessimistic. If you release your code under MIT or BSD and _ask_ people to contribute back if they improve it, most people actually will - I don't think I've ever used GPL and I've gotten hundreds of patches for projects of mine. People don't contribute to open source because they're forced, they do it because they want the network effect of everyone else contributing and they want the software to be better. However, GPL says "I don't trust you, and I don't trust you so much that I'm going to legally severely limit what you can do with my code unless you promise legally to share my philosophy". It's not only frustrating when you're trying to figure out what you can and can't do with it, but it just seems kind of mean-spirited. It implies that they feel that if they don't legally force you to, you'll try to take advantage of everyone, which is sad. Maybe I want to use a library for a commercial application and would then be able to spend part of my work day improving it - if it's GPL, it's use is not even an option assuming that the company will not open source the main product, if it's not GPL than both the library and the company benefits. I guess at the end of the day, I just don't care if someone takes advantage of some of my code - several of our GitHub competitors use our MIT'd Grit library we use to run their own sites, but honestly we don't really care - we'd rather have a larger user base and volunteer pool and let even our competitors be able to contribute back than shut everyone out because we are so distrustful and protective of our code and time. I just think that asking is more effective than threatening, and to me the GPL is threatening.