Upgrading without need can be a poor decision.
Upgrades which provide security enhancements and other features and benefits which you and your community need and want - can be good decisions.
I'm still using EE 1.7, which I think is about 4 years old. It works fine. The upgrades to it, reportedly, do not.
Lazy and conservative here. In my businesses we always made sure we had plenty of stock of the tried and true products as well as the "newest thing". In almost all cases, the older stuff outsold the newer and therefore was more profitable for us - and, with less problems, better for the customer.
But don't get me wrong! I'm glad lots of folks upgrade on the day the new stuff is available. They are my test sites!