WPCS is nice, but very far from being flawwless. For some things you need to uglify your code in order to reduce the noise coming from it, which is not a great thing. If for example you want your code to be easily testable by having functions returning html instead of outputing it, good luck with reducing the amount of "non escaped output" warnings.

Coding standards should be a connivance for the developer, helping him to read his old code and search for anything in it, it is not by itself a good measure of the quality of the code, you can write a totally insecure code that obey all coding standards.

While it might be a good thing to nudge wordpress developers into using some mostly common coding standards, I am afraid this information will just create a false sense of security with users, and there will obviously be false warnings as well. If this information will have an influence on search results, or any thing else, all you will end up with will be a better and more maintainable malware code.

I assume that applying such tool on the repository will force Otto to kick his "php in widgets" plugin out of it, which lol is unlikely to happen, so we will end up again with the tired old discussion about arbitrary decisions in the repository :(