It was considered “reformulation” back then. By today’s standards, it’s a conference paper and publishable if you combine it with politics.
The diagrams would certainly be criticized today that they are graphical illustration of known expressions, not new and certainly not rigorous.
Also, path integrals were taken right out of Dirac’s so called little paper and Norbert wiener’s papers. Dirac thought they are straightforward but not rigorous and was busy with other stuff anyways. Again today if you propose something like that, it would be rejected on the ground that it’s not rigorous.
Feynman diagrams were criticised at the time. Dyson showed they were equivalent to Schwinger's methods, then people gradually realized they were physical as well as helpful.
Perhaps, but that's not an indictment of Feynman, but an indictment of how you get a PhD nowadays. Today you get a PhD for something rigorous and technical and ultimately irrelevant compared to Feynman diagrams and path integrals.
In life, you sometimes learn that what is mathematical or cutting edge is not always synonymous with useful or revolutionary.
"Hackers" of 1990s were just script kiddies by today's standards, because the "bar was low". That doesn't make them any less important as far as contributions go.
All in all, maybe you are right, and maybe he is somewhat of a showman. But perhaps that is what we need more. Someone who masters science but also is human.
Do you also want to say that Newton’s Principia is now high school physics? What was pathbreaking at one time is run of the mill now. That’s called scientific advancement...
Today a PhD student would come up with something like path integrals and would barely be granted a PhD.
Real science and showmanship are different things.