Having high tech doesn't mean you can really fix it without the base technologies they are built on.
And if the people who had that knowledge got wiped out with the bombs.... the survivors would have nice toys but no way to make new ones or make replacement parts for old ones.... and things would head for a dark age (as seen in fallout)
This is why the Enclave continued to develop, and most everyone else slid backwards. (as far as I can tell)