There Is One Well-Known Defect
It is that theoretical physicists have spent the last 45 years in self-absorbed mathematical diddling while virtually ignoring the physical world of nature that they are supposed to be explaining. This has led to untestable pseudoscience in the form string theory and its egregious “multiverse”. It has also led to a succession of failed ideas like GUTs, magnetic monopoles, supersymmetry (and its AWOL spartcles), WIMPs (also AWOL for 40 years), extra dimensions, and imaginary particles/fields beyond numbers.
There has been precious little gained from all this diddling, beyond a lot of hype.
I think we need to change tacks and study nature for a change. Here is a start in that direction: