I'm very happy with Photoshop CS6 and Illustrator Cs6 and and a few other CS6 applications.
I signed up for InDesign Creative Cloud so I could have the latest and greatest in InDesign.
There's always been backward compatibility issues - and they are outlined here as to why http://in-tools.com/article/whats-with-back-save-to-earlier-versions-of-indesign/
And every new issue of InDesign there's always a group of people displeased with there being no compatibility - and it's not because Adobe don't want it, it's because the new features are so complex that opening them in an earlier version of the program that didn't have that feature would InDesign to meltdown, melt a hole in your floor, and straight to Earth's core. And nobody wants to see that happen.
The subscription model is a fair model - you can still have CS6 or earlier installed on your computer and only use the latest InDesign if you wish to.
It's completely up to you to how you handle the upgrades. And you can choose to ignore them altogether.
But basically - the subscription model is here to stay and you can't buy a perpetual license any more.
And in fairness, Adobe are not the only company doing it. It's a system that brings in perpetual income to their company, so they can employ more staff, develop new areas for products and it helps to fund the projects they are working on. And this in turn is churned back out to the user. It's a perpetual cycle of life.
But it's up to you if you want to be part of that cycle or just be happy using the older software and get your job done.
