I just read OLD MAN LOGAN, and you're 100 percent correct. Almost the only points the movie has with the GN is that Logan is old and full of regrets, and that some unspecified disaster has taken the X-Men off the map. On the whole OLD MAN is just Millar rehashing the same tropes of his first major hit, WANTED, and once again (IMO) Hollywood made a silk's purse out of a sow's ears by taking a few basic concepts from the GN and taking them in a more human/humane direction.
No wonder the director of LOGAN kept emphasizing SHANE; that's probably the sort of work he wants to be associated with.