For professionals used to Photoshop, yes it is that bad. People want what's familiar because they're used to it and they're busy or lazy. They don't want to learn something new.
If GIMP wanted to increase their userbase by a million overnight, they would make it look more like Photoshop.
The problem is they and many current users are huge FOSS zealots and see this kind of thing akin to selling your soul to the devil.
I think this is more of a failure of the license itself. It's not a good look to allow something explicitly and then go "no not like that!"