Re: subtle leap-froggingatch
Unfortunately watchOS 2.2 came out in March, so calling it 2.1 might lead to confusion.
They're calling it 3.0 because they've made cosmetic changes to the user interface, performance changes to the main OS and introduced a bunch of new APIs for developers to use. I'd say it was fair to call it a new major release rather than 2.3, because a point release doesn't usually have anything more than half a dozen new features and some bug fixes.