While I understand where you’re coming from, I believe that it distracts from a massive positive effect that the GPL has: the way it ensures collaboration. Lots of contributors to GPL software do so in the knowledge that they are working on something great together. I myself have felt discouraged to contribute to MIT licensed software, because I know that others might just take all the hard work, make something proprietary of it and give nothing back.
I see GPL as some sort of public transaction, it is indeed more limiting than MIT and offers less pure freedom in that sense. But I just love how it uses copyright not for enforcing licensing payment for some private entity, but enforces a contribution to the community as a whole. I find this quite beautiful.
Xonotic is still quite active!