Google released the latest report on Android version adoption for developers, and things aren't looking good for Lollipop (Android 5.0). In fact, Lollipop is nowhere to be seen in Google's chart. That's because Google only shows the versions that get over 0.1 percent market share, which means Lollipop couldn't even gather that much in the month or so of availability, even though it was a holiday season.
Given that the Nexus 6 was so large (6 inches), Google may have underestimated its popularity and made too few of them. The device has been constantly out of stock, which simply means it had higher demand than Google had anticipated.
However, even if Google made more of them, it's unlikely the device would've been overwhelmingly popular. Last year, the KitKat version managed to gather only 1.1 percent market share thanks to the Nexus 5 and other Nexus devices that got the upgrade. That's compared to Apple, which had 50 percent of its users on iOS 8 within weeks of the launch. For iOS, that is actually a rather slow adoption caused mainly by the introduction of many bugs in iOS 8 compared to the release of iOS 7, which led many customers to postpone the update.
Android Lollipop likely won't see too much adoption until popular devices from Samsung, HTC, Sony, LG, Motorola and others start receiving the Lollipop update in the first half of next year, along with the introduction of new flagship models that will come with Lollipop out of the box. This also means there is at least a half a year period in which the vast majority of Android devices can't experience Google's new OS, after its "public release."
Some of that delay is caused by OEMs building their own customizations and apps on top of the new version. Google made Android open source, which helped it grow exponentially faster than it would've probably grown otherwise, but that also came with a downside, at least for consumers. The manufacturers can usually modify Android as much as they like, as long as they maintain backwards compatibility.
This makes it impossible for Google to release Android in the same way that iOS, or even Windows, is released. Apple can release iOS for all of its devices at the same time (granted they are not older than three generations/years), because the company does the work for porting the new version and supporting the older hardware before the software is publicly launched.
Microsoft usually works on its new OS internally for some time and then has a "preview" period in which the OS is mostly finished, from an API and feature point of view, but it's not actually released, because Microsoft waits until most OEMs are ready to ship new machines with the new OS. This is better for Microsoft, it's better for manufacturers, and it's also better for consumers, who all get to benefit from having the new OS at the same time (if they want it).
Google takes a different approach from Apple and Microsoft. It tests the new version just on its own handful of Nexus devices, which represent a small portion of the market, and as soon as that's done the company releases the new OS for Nexus devices, leaving all the other devices in the cold.
Google did begin having a "preview" period as well with the Lollipop version, but it doesn't seem to have helped nearly as much as it should have, mainly because Google's preview was still very much in flux, with many APIs changing by the time the final version was out.
This led even the CyanogenMod guys to say that they were not going to work on the Lollipop version of CyanogenMod until Google released the final (and stable) version. A "preview" is no good for manufacturers either if they can't rely on the OS to stay mostly the same when they start porting it to their hardware. There's also no point in starting to put their customizations on top, unless they are willing to deal with significantly rewriting some features once Google modifies some APIs before release.
Although the Android situation is a little more difficult because OEMs want to change the way the OS looks, Google could still partner with them to ensure a much smoother public release of a new version of Android that's available on day one.
Google could help this by building standardized customization engines for Android that OEMs could use (such as an advanced theming engine, for example). Customization that Google would "control" would be much more desirable than customization it doesn't. However, that customization engine would need to be advanced enough or the OEMs may not want to use it.
OEMs could also focus more on differentiating through apps rather than built-in OS features, because that would be a more modular approach which would allow them to release new versions of Android even if some of their apps have to stay the same. Google itself has taken this approach, trying to decouple many things from the OS, including the keyboard and camera apps.
Android still suffers from an update problem as much as it ever did, which affects user experience and also the security of those devices running old software. Google and its partners could do much more if they worked together to improve how fast Android devices get updated. They could also be more organized and release a new version that everyone can have at the same time.