The reason you're not seeing Android updates being sent to your phone in a timely fashion isn't down to the software customizations carried out by the manufacturers, but rather the hardware differences between Google's latest handset and other handsets already out in the wild, claims a Motorola executive.
"When Google does a release of the software, they do a version of the software for whatever phone they just shipped," said Wyatt. "The rest of the ecosystem doesn't see it until you see it. Hardware is by far the long pole in the tent, with multiple chipsets and multiple radio bands for multiple countries. It's a big machine to churn."
This makes a lot of sense, and highlights that the problem with fragmentation is primarily down to Google pushing out new releases of Android faster than the manufacturers can get their acts together to support the new release. By the time a new version of Android is released, Google is already thinking about the next release, so manufacturers don't have enough time or resources to both implement support for the new release on older hardware and plan for the future one.