Don't force users to update

Why nokia and google force users to update to next android while the newer android can have a lot of bugs and can affect thier work!

I hope nokia does not force it, and give users only updates to fix current bugs on the current installed android version.

If new android updatd come to phone and i just bought it and want only to update the current system to last update, and don't want to update to the new android because i cant risk my work experience on phone, how can't i do this !!