What made Feynman a great scientist was that he could explain hard things in a simple manner. If you can't explain it simply, then you don't understand it well enough.
Try to explain that to string theorist. No wonder quantum mechanics isn't making progress. These new scientists just want to prove how smart they are, and not how
little they actually know. Thus allowing them to make progress.
Upthread commenters have suggested that Carl Sagan and Jim al-Khalili are comparable to Feynman as explainers of physics. Sagan was good at communicating a sense of wide-eyed awe; al-Khalili can tell a story well. But they both stay well clear of really hard stuff in their popular expositions.
Feynman, on the other hand, didn't seem to have a sense that there was any "really hard stuff". Fools rush in where angels fear to tread (I don't mean to suggest that Feyman was stupid, rather that he was a great joker).
Try to explain that to string theorist. No wonder quantum mechanics isn't making progress. These new scientists just want to prove how smart they are, and not how little they actually know. Thus allowing them to make progress.