One of the annoyances I've had with Android, from a new consumer's point of view, is that it's presented as this monolithic OS that's the same across every phone. But once you do the research, you find that it's really not. Except for the Nexus line, there really isn't a "Google Android" experience. When you buy an Android device, you're really buying HTC's, Samsung's, Amazon's or Motorola's Android. Every device has different capabilities. Some ship with different Google services out of the box, others ship with their own internal apps. Google's Android strategy is that every manufacturer can make their own Android shell, without placing any requirements on the vendors as to what version of Android they're using.
It's a great thing that there's all this choice for the devices. It's a great thing that Android allows this kind of freedom. But it's led to a lot of issues for Google and for developers.
The problem that Google has is that they've effectively lost control of Android. They can't force manufacturers to use the latest version of Android. So they're left with situations like this, where the vast majority of Android devices are running an old version of the OS, and will never be updated to the newest version, because the manufacturers just don't want to[1]. So the result is that they have to support around 4 different codelines at the same time(ICS, HC, Gingerbread, and Froyo).
It's a problem for developers because your display code might not look right on a new device with a weird screen resolution. Or you might need API calls that are only in 4.0, which would lock you out of 90% of the devices right now.
No, the alternative is for Google to exert control over the device manufacturers and state that if they're going to be using the Android OS, they need to support and update their devices to the latest version for at least 2 years after the phones are released.
[1] There is a good economic argument that patching phones that are 18 months old with 24 month contracts about to be up just doesn't make sense, but honestly, it comes down to that the manufacturers just aren't willing to do it.