The TWOK adaptation was (belatedly) done because it was the only Trek movie not to have a comics adaptation, and some people found that unacceptable, because they wanted to see what it would look like as a comic.
Or, it was purely a marketing decision by IDW, who wanted to do a collection of the adaptations of all 6 TOS movies, but they had a big hole -- the one widely considered the best of the 6 had never been adapted to comics. So they did it as a comic just to have the material available to collect.
Not that there's anything wrong with that.
I notice they haven't made any moves towards adapting Insurrection
in order to fill out a TNG Movie omnibus (which could also include the adaptation of All Good Things