I just want to chime in to say that our university has purchased a decent chunk of GMS2 licenses via the educational pricing, and it's working for us.
There's points to be made on both sides, of course. The university where I work has a very prominent undergraduate gaming program, and we use Unity and Unreal the most when we use an engine, but we don't actually use engines a lot... Students doing projects on VR experience, or UX stuff like "how does a character's walking 'bounce' affect their immersion in a game," or mucking around with some kind of shader for a novel use will pop into an engine. In other words, students use engines when the "real" course work involves a specific angle to study, and needs a basic gaming experience tossed together in 1-2 weeks as a platform to do the study, but one dev tool is not the focus of the curriculum. (Heck, when I started working there, Unity didn't even exist)
So, having GameMaker installed in one large computer lab, and having students use that lab has been fine. There's 2 classes that use it to focus on mechanics and game logic, where fancy APIs cloud the issue, and the lab is sufficient for the need. Actually, since students aggregate there when assignments are coming up due, they get a lot of collaborative help that way; added benefit.
I'd *love* to see a free version, of course, so that our students would extend their GameMaker work beyond class, and I could argue that there's a quarter-generation of young people who are entering the marketplace without a serious dependence on GameMaker due to the lack of a free license, which leads to lower adoption when they get real gaming jobs. But realistically, numbers don't suggest that the free GMS1 led to industry dominance, so.......what would have changed?
GameMaker really just suffers from an image problem. I mean, everyong likes free, right? But people are willing to shell out money if they see themselves getting something that does "enough for what they need" at a lower price than the "Big Expensive Pro Software." Graphics people buy little sprite-making programs on Humble Bundles, for example, and are darned happy that they didn't pay full price to the Adobe Overlords. Then, YYG sells a game making tool, while Unity and Unreal are giving theirs away for free--it puts YYG on the wrong side of popular perception.
I feel like YYG is trying to be something like "a decent set of those little affordable dev tools like you see in Humble Bundles all in one integrated package" and also "a complete environment for rapid game design ideation" rather than being just another IDE that compiles flipped assets and sweet shader tech into games. The combination there is more and different than the free tools but hasn't come into its own market category yet. And we need a lot more Undertale success stories to really make clear the value of the royalty-free license. Shrug Keep on keeping on.