Poor you. The game industry _chooses_ not to go near GPL'd code because they want to sell proprietary software. Counteracting the existence of companies doing proprietary software is the very reason why the free software movement was started in the first place.
Yes, the free software movement is supposed to be detrimental to the developers of proprietary software and has no incentive to cater to their needs. Do you think we want to make Windows or iOS a more attractive platform? Or to build components to be used to improve proprietary engines instead of helping free ones because hey, the proprietary devs may send a bugfix our way? No.
MIT-license users are not bad guys -- I have both GPL and MIT code out there myself -- but choosing a non-copyleft license because it helps proprietary developers is not a good reason. I chose MIT to interoperate with other free software; if it wasn't for that I would have chosen the GPL or the LGPL.
> hurting our entire industry
I think the entire software industry is _helped_ if I drive it towards free software. I don't care how many billions the next Call of Duty game will make. I care if local developers in my country can get a consulting gig because the system my government uses is open source and so they have a shot at fixing its bugs instead of having my government sign a multimillion dollar contract with a major foreign company and get locked-in to it.
> (Programmers with zero options; they're not going to ragequit the gamedev industry just because engines are closed source.)
Weak argument. Back then would you say "system programmers are not going to ragequit the industry just because operating systems are closed source". But instead, they wrote open operating systems. Follow their example. Write a free engine. That's the entire point.