Re: John Harrison was more interesting than (SPOILER)
It does feel like somewhere in the process they went from Harrison to the Khan/Harrison villain. Maybe as late as shooting the film.
I think the Harrison facade could have been done away with completely and wouldn't have changed the movie much, as well.
"When I first heard about it (the Enterprise underwater), my inner Trekkie was in a rage. When I saw it, my inner kid beat up my inner Trekkie and made him go sit in the corner." - Bill Jasper