When considering Android market share you have to account for the millions of cheap phones out there that nobody buys or uses, often with a no-frills, crappy version of Android installed, that still counts towards their market share. The quantity of Android-based phones doesn't necessarily represent a quality experience across the board. It's the same as Microsoft licensing Windows out to anyone who wants it regardless of the quality of the machine it runs on.
It must be a nightmare for developers trying to write apps for an Android platform when there are hundreds of hardware and software combinations out there to satisfy, instead of a small set of devices and software versions on iOS.
That said, Apple still has to take it seriously and not take it for granted like Blackberry did.