I see usually two options:
a) Solution X does it generally better than Y and their solution is *ported*.
b) Adapt to solution Y. The end.
Most of the time it is b. Because Vim shall not be Emacs. Linux shall not be Windows. And macOS shall not be Windows either.Do you remember that foolish Windows-Themes on Linux? Luckily GNOME has killed custom theming. And Apple also. Custom theming is a horrible mess aside from areas where it is intentionally (e.g. Vim color schemes).
But it is also possible that Gimp moves to option A. At some point and they are interested in user-interface improvements. Most people just want to use Single-Window-Mode which shall be default for many years.
> Do you remember that foolish Windows-Themes on Linux? Luckily GNOME has killed custom theming.
In what way has GNOME killed theming? There are lots of themes available on [1] and some of the most downloaded ones are consistently imitations of the latest macOS or Windows style.
Custom themes for DEs and the like are fairly important for accessibility.
c) There's a sane, standard way of doing things that everybody is familiar with, but you do decide to actively go against it for decades because you like doing things your way, and if anyone has anything to say about it they're "free to fork" and you "don't owe anyone anything", but despite that, everyone should use your thing because it's free and you're the good guy, and otherwise they're supporting the empire of evil.
This is why Krita is sweeping the floor with gimp - sane UI that's way closer to Photoshop. You need to rebind 5 things and you can use it.
> Luckily GNOME has killed custom theming
Same deal. What do you care what I do with my computer? GNOME is hanging on by nature of being the default, but very few people pick it when they have the choice. It will be dead in 10 years.