Samsung is frequently referred to as "the only android carrier that makes any money". One wonders whether such Apple-sque upgrade forcing has contributed to their financial success.
Apple doesn't 'force' upgrades anything like what every Android vendor does. The iPhone 4 is now 2.5 years old and still happily runs iOS6 - I can't find anyone with a 2.5 year old android phone that's running current software that hasn't modded it.