It's a mixed bag.
It is absolutely mandatory that developers work in the most current package. I've been dealing with it since the first release, and granted it's a PITA but one of the inconveniences that are accepted as "cost of business".
Also bear in mind that it's not just P3D. Now there are three platforms with the addition of FSX ST that has it's own evolution curve looming.
I have the advantage of being able to devote full time attention to sim related work, and have developed a work flow that allows for the inherent lag as peripherals are updated. Agreed, it's not easy and my wife has learned to tolerate the occasional sim induced Tourette.
I'll jump into V3.1...I've done over three dozen installs of P3D to date...and make adjustments on the fly. No pun....
For me personally, the cost benefit still justifies the extra effort, but obviously, may not be for everyone.