You do realize that for most Android devices, "rooting" requires finding a security exploit first to allow escalation of priviledges to root? It is not officially a part of Android and is not really blessed by the OEMs.
From a policy/ethical perspective, if you have to find a security exploit first to completely own your device, how is Android OEM policies any different from Windows then?
Every android device I've owned has been freely rootable. Maybe there are some that are more restrictive, but all I've had to do is change a setting in a menu.
Whereas the Win8/secure boot ecosystem is an active pain to dual boot, where it doesn't just downright block it entirely. I had a Win8 laptop that I bought recently, it was an absolute pain in the arse to get anything other than windows booting.
Google has always made the distinction between AOSP and the closed-source suite of apps they license. Nothing about AOSP licensing has changed since the first code was released. Significant and expensive-to-develop enhancements to the Android OS, like ART, got released to AOSP before they were shipped by OEMs.
At least Windows and Microsoft still means what it always did.