I wasn't complaining about the slow release. Just giving the reason I think it is taking so long. Disclaimer: I am running CM 12.

The difference is the large scale of change in the OS. Google have changed the default runtime to ART. Breaking a lot of manufacture skins and bloatware. Obviously this makes porting Lollipop a lot harder then the transition from 4.3 > 4.4. Hence why the slow release from manufacturers.