I've felt this sort of frustration at times when I've asked for features and gotten responses that I felt were dismissive or not helpful. So I get that.
I don't think how you're going about this is at all productive though. Lumping a bunch of additional vague negative criticism about UI polish and whatnot... what does that accomplish? YYG are working hard on their product, and are actively participating in these forums. They
are here listening and they
want to hear from users.
But if you have points to make about UI polish, you need to make those points very specifically, and probably separately from one another, so each can be addressed in turn. Going off topic in a rant here when you're frustrated that you're not getting the answers you want to hear about your other concerns just makes you come off poorly, I'm afraid.
As far as building engines, addons, and tools, sometimes you do need to make those things, in order to make the game you want. The trick is to make those things only when you need them, so making them doesn't distract you too much from making actual games, and to make them in such a way that they are generally useful, and re-usable for other projects.
This gives them lasting value and they won't be such a waste of your time that way -- indeed, you'll find that as you build up a toolbox they will tend to speed up your development, since they'll already be built and allow you to do more with them than with just GMS alone.
And as you build them, you'll also be building your skill at programming. Any programming work you do will make you a better programmer, and the better you get, the faster you will be able to develop. What may seem like a waste of time now will enable you to be so much faster in time that it will actually save you time in the long run.
Any sizable game project will involve creating utilities that support development of the game, in addition to the game itself. YYG can't be expected to provide everything anyone could ever need in that regard. They give you the bricks; there's infinite ways to put them together, so you have to put them together the way you need them.
Once you have those tools well honed, you can share them or sell them as you like. This is appreciated by the community, and will earn you respect of your peers, credit for providing assets that benefit everyone, and bolster your reputation.
It's also fine to make requests of YYG to add things that you'd like, but you should respect when they say no, especially when they give reasons. It's their product, their business.
You're their customer, and obviously it's good for them to be receptive to customer requests. But you're
not the
only customer, and they have to do things that are in the best interest of the business overall. Having given you the response that they're not implementing something, this at least tells you that if you do it yourself, you won't be competing with some future release that they may come out with down the road.
GMS1.x had no autotiling built-in, so people had to come up with it on their own. GMS2 has 16- and 47-tile systems built in, which is a terrific improvement. Unfortunately they don't have what you need for your project, but that's to be expected -- at some point you have to build your own thing.
So go on and make a 9/10-tile autotiler script yourself. Make it good enough that they wish they had done it themselves.