What I got from his interviews is not that he disliked the GoL, it's just he disliked the GoL overshadowing everything else he did (basically, becoming the GoL guy). He personally didn't see much more interesting mathematics that could be done after answering basic questions like universality (although it's likely he wasn't aware of everything the community was up to). Also, it's clear he seemed to come to terms with it in his final interviews (including the second one you linked) :)

I've played around with several CAs and Conway's rules stands out to me as one of the most interesting still, for many reasons (like simplicity, interesting patterns, long lived structures).