I'd argue that GIMP reclaimed the word for a better meaning. Consider how the word lame has lost its derogatory impact. Googling "gimp" gives me only results about the program. Changing the name now would dilute decades of brand recognition and confuse users, especially those in non-English communities.
I think the sunk cost into branding is the right take here; my 2¢. Gimp is still niche, and will never be used the same way people say Photoshop when referring to any general photo editing. It will take quite a few more years of transient language and lots of success for that unrealistic outcome.
