Have you considered changing the license of Wesnoth to MIT so commercial game developers can use their time and effort on components can port them to their own projects too?
I can't justify investing hundreds of hours programming new components a project (even one I'm passionate about) that a later derivative can't be used by my company.
I could elaborate.
In fact in this situation you would be better off with Wesnoth as GPL rather than MIT, because that way your closed-source competitors can't use your component in their games.
Ehh, but there's no direct monetary loss. Not many games stay relevant for a decade, so it's likely the commercial competitors will drop support after X years while you can backport their blackbox improvements. That said, I wonder if components of games are really that able to be copy pasted. My initial impression is NO, unless that was the intent when the component was first written.
The license wasn't chosen randomly - it's there exactly so you can't use their time and effort by porting their components to closed source projects. It's not an unintended side-effect.
As a stop gap - they can implement a contributor clause starting immediately. They can also say future commits post-[ref] are <this license> until the prior code is sunsetted.
Typically there is an uppercrust where a very high percentage of the contributions lay. I haven't looked at the code (played the game all the time back in HS) but I'd bet you 90% of the code contributions are with the top 5 committers.