Contrary to the beliefs of most musicians who are inexperienced in recording, extra noise isn’t always easily fixed during the mixing process. Besides, wouldn’t you want your mixing engineer to be more focused on improving your song rather than trying to fix it?
All intervals in 12-TET are the same size, regardless of starting pitch. Furthermore, all keys are comprised of the same interval relationships, so they’re completely interchangeable. In 12-TET, you can hop around from one key to another at will without having to stop and retune everything. That is pretty awesome.