The new trilogy isn’t about Luke, it’s about the next generation.
That becomes clear from the films, but that wasn’t the only option, nor was the execution of the “passing the torch” concept set in stone. As far as I can tell he doesn’t have a problem with passing the torch, but he does have a problem with its execution. It also appears through various interviews in the past, that he is also privy to Lucas’ intentions with his character, which appear to clash with what was put in the films, and he’s conflicted about that.
Alec Guinness was a great actor, but he didn’t go on and on abut wanting to be the focus of the trilogy. He was killed off in one movie and was a Force ghost in the other two. Mark still needs more training. “Train yourself to let go of everything you fear to lose.”
That doesn’t seem a fair comparison, as Alec Guiness and the Obi-Wan character was a side character to begin with. Luke Skywalker was a main character in the OT. We watched that story unfold through Luke’s eyes, and Mark lived through that. It seems logical that many people including Hamill himself have grown attached to these characters. Some of us simply feel these characters’ arcs in the OT were sacrificed in order to push new characters into the limelight, and that these new characters aren’t up to snuff in a setting is way too contrived, and familiar, because the powers that be feel that a Star Wars trilogy without Empire vs rebels, x-wings, and tie-fighters is a harder sell to the general audience.