Who's really got skin in the game? Perhaps the author who spent countless hours pushing the project along all those years, he took all the risks and uncertainties. Yes, all contributions did help but being a humble contributor I wouldn't ask for any kind of eternal obligation. Otherwise what kind of help is that? If one wants to give, they just give, full stop. Why not stick to free will? Notice the word free.
If you feel this way you should never open source your work. Licences like the GPL as well as licences like BSD/MIT explicitly allow for forks like this.
