He has always been out there sharing stories of the Beatles and portraying the band and its members in a positive light (whether deserved or not). And that’s what Beatles fans want. I was happy to read not too long ago that McCartney and Starr FaceTime each other every couple of weeks. McCartney clearly cares about the band’s legacy.
McCartney, of course, had a great music career after the Beatles, so he’s admired for that, too.