that is not hypocrite, is due GPL, you can't go to forum and send contributions with your credits, if these are not really maded by you, anyway you can take work from others forks ofc, but you should always maintain the credits.
nobody call L2J retail, we just says that L2J focus in retail things more than custom things. this means custom contributions have always low priority in L2J.
Aggro in skills and hate skills is done since years, about others features is a common issues of any open-source project, sadly but is true that if you don't pay for real devs, this things happens, similar things happens on linux when you talk about desktop/user friendly side.
I don't see other L2J/Forks forums more active, about boneCP is not easy to say let's commit it and ready, that is not the good way, because is a critical lib, and that require proper test, benchmark, etc.
we can't do nothing with that, due is part of human nature, and you should know that there is people that prefer making things for money and self, instead of for free and all.