Yeah, I know. At one time though, version numbering was used as a signal to other developers that relied on your software. Changing the major version number indicated a large change -- either API, or architectural, or both -- that was expected to break software that relied on it. So then, as an end-user, it was easy to keep track of which pieces were likely to be compatible with which other pieces; if your add-on or what-have-you worked with version 2.1, then it would work with 2.1.1, and probably work with 2.2, but probably not work with 3.0.
I guess people got bored with the sensibility of that, or something.
Linux has kept its main public interfaces stable for all of its several hundred post-1.0 releases, so using that scheme would mean Linux would have to use rather odd-looking version numbers like 1.632.5