GIMP is not trying to emulate Photoshop. That is their problem. Really, they should ape every single one of Photoshop's functional features.

Photoshop is the standard in the arts industry. Photoshop is also darn good at what it does, certainly no competitors even in the proprietary space. There were at one time: Corel Photopaint , and Paint Shop Pro and so on. Photoshop won that war for a reason.

GIMP needs to be a FOSS Photoshop first. And if there are improvements they can include them. Like dumping GTK and using Qt, for instance.