I tend to agree with you. GIMP is a very important project in my view because it provides legal, cross-platform access to a baseline of image manipulation tools. The above-and-beyond feature set is fantastic, but not the reason why I love it.

I suppose this isn't directly related, but following the theme of OSS alternatives to commercial software... after being ignorant of the OSS desktop application world for a few years, two cross-platform projects have blown my mind recently with their feature sets and level of polish:

Natron - https://natron.fr/ - Node-based video compositor. I've used it to add some dumb special effects to videos.

Godot - https://godotengine.org/ - Unity-like game engine and IDE with export to all non-console platforms. I've used it to make some dumb games.