Thought I'd make a return
It's not the OS itself which is wank, its sometimes the manufacturers
Look at 2 of the biggestplayers on the planet
LG - The Optimus 2x was left untouched at Gingerbread leaving users to root and install custom ROMs long before an official ICS release came out
And the Optimus 4x - Currently at JB, the Hardware should run KitKat with ease if it gets it.
Now look at Samsung - Galaxy S2 - Froyo, Gingerbread, ICS, and Jelly Bean those were all official updates, the orig Galaxy S stopped at Gingerbread
S3 - ICS, Jelly Bean
The reason must be software development. Manufacturers and operators want to customise/test the ROMs