It didn't introduce many new features to the OS itself, but it changed quite a bit.
If the company decided that developing the old version isn't worth it then giving them a free upgrade path seems acceptable but selling software that is obsolete a few months after someone buys it reflects poorly on our whole industry.
My company insists that I shouldn't update to High Sierra because doing so breaks several well-known apps, including Microsoft Office (albeit v2011, I think?). So I haven't updated, and... everything is fine.
A demand for a free upgrade path suggests to me that all software ought to be sold as lifetime licenses with unlimited upgrades. I think that extreme would undermine our whole industry far more than a company insisting that only their latest product is supported on the latest operating system.
[0]Here's Apple release updates for Sierra, El Capitan, and Yosemite very recently: https://support.apple.com/en-us/HT201222
Also to suggest that High Sierra is a simple maintenance update also dismisses the large number of apps that no longer work with Mac OS. This is a big big change and you need to decide if you should consider updating given your reliance on Bria 4.
I really do think the OP is blaming the wrong people here. Apple has a lot to answer for.