Surely Google is not intentionally refraining from solving the high fragmentation it is suffering from (which makes developing for Android harder, and keeps some people from receiving security updates)
Because it causes friction, it's a distraction for management, and there is a danger that some of those rebel handset makers could have some success or get poached by Microsoft/Bing even if they fail at creating an alternative OS.
There is risk without much upside for Google compared to the gradual approach they are taking now.
Surely Google is not intentionally refraining from solving the high fragmentation it is suffering from (which makes developing for Android harder, and keeps some people from receiving security updates)