I hate using this term, because it gets overused on the internet... but I think the lightning in a bottle analogy is apt for Pixar. They just assembled and nurtured an incredible roster of talent, the kind that was probably only really possible with the dawning of a new technology. Even if John Lasseter didn't have the problem with the, um, huggies, the old gang was eventually going to move on in their own separate ways. Who is still left there from their original Murderers Row creative team, besides Peter Doctor?
Maybe Chapek didn't give Pixar the love they needed, but in retrospect, it seems the division was already past its prime by the time he took over. Especially because Disney Feature Animation has long since found its footing in the CGI era, after some initial stumbles.
On the other hand, Chapek never seemed like the right type to recruit and nurture creative talent.
And I don't think you are mistaken, Luca was much better received than Raya.
The technology was a nice novelty when Pixar started, but it was hardly the main reason for their success. Others tried, including WDFA, but nobody achieved Pixar's level of consistent success. Pixar simply made good films. Sure, they knew the tech had tremendous potential. But they never forgot they were still making movies, and unless you are striving to be a one-hit wonder, the tech would not be enough.
Storytelling talent is always available. But Eisner's ego drove away the talent he and Wells attracted, and Iger, never one to shy away from an acquisition, understood the quickest path for Disney going forward was to mend the Pixar relationship and bring them in.
Pixar, who oversaw all Disney animation, quickly got the Disney side on the right track. But with Disney corporate calling the shots, Pixar is slowly being assimilated (Remaining in Emeryville has likely slowed the process). It's still a quality unit and it still produces quality films, but telling great stories is no longer the sole agenda.
Hard to say if Chapek has an ego to match Eisner's, but clearly building and maintaining relationships was not his strength. Nor does he value quality and talent all that much. While Iger is no visionary, he is much stronger than Chapek in those areas.
Bottom line, Iger was shepherding Pixar on a slow roll to mediocrity. Chapek, as he was doing with most of Iger's issues, was fast-tracking the process. We'll just have to see where it goes from here.