They refuse to do the same because migrating from GTK 2 to GTK 3 took 7 years to achieve with a diminutive team and they still implemented a multitude of requested features.

They’re not refusing. They’re actually doing the opposite. But they needed to get their house in order first.

The 3.0 upgrade was the result of the getting their house in order and modernizing. Doing cosmetic changed before hand would have made no sense because those changes would have been thrown away when they would have to modernize things anyways.

I think I have an analogy.

Gimp was like an old American style wooden house that was flooded. After the water recedes you could try to make things look nicer by plastering and painting the walls etc. But as goes with flooded houses if you do this the mold will rot everything out.

In order to save a flooded house you need to remove all the dry wall and use fans to dry out the internals. Once things are dry then you can plaster and repaint things.

Gimp 3.0 was them ripping out dry wall and air drying the internals. Now that that is done it now makes sense to clean up the UI.

If you clean up the UI before you dry the walls out it’s just a waste of time because those improvements would need to be ripped out with the dry walls always.

It’s not perfect as far as an analogy goes but it’s close. Gimp should have never let the house flood in the first place. (Analogy breaks down here a bit). But since they did. They needed to fix the fundamental before it would be worth fixing the UI.

This all being said they could at this point genuinely refuse to change things UI wise. I hope they choose to pull a Blender or Krita but they don’t have to.