It's the fault of those wanting instant gratification - those who wait in line for days for the latest shiny toy when it's possible to just wait a few months. Look at the minor revision of Apple's software to refer to this chart:
10.0 - alpha unstable pre-release for unpaid testers
10.1 - beta release for those who enjoy reporting bugs
10.2 - official pre-release for those who will accept a few bugs to gain a couple of extra features.
10.3 - first stable release. Be prepared to be disappointed.
10.4 - most but not all bugs have been squashed. You'll have to learn to live with any remaining bugs.