I have good skills and development tools for the Web and Mac OS and Windows. So that's where I develop. If I have my way I'll be able to continue doing that indefinitely, but I worry about Apple and the future of the Mac. I have a feeling the same reasons I can't develop for IOS will turn out to make the Mac impossible for me to work on. Or maybe I'll have to stop updating my system at some point.
For a while it seemed that Twitter was part of the platform. The API was open to anyone, and was largely unlimited. It was an open notification system for the web, which I thought was a really neat idea. Over time it's become more and more restrictive, and eventually I lost interest. It would have taken a lot of work just to keep my apps running on Twitter, and I didn't have any more ideas I cared about. Time to move on.
Can't develop for IOS, my software does not even slightly fit into their idea of an "app" -- so that's not an option.
So that's me. What about users? I think more will care over time, as the corporate platforms restrict what they do more and more, and extend their reach into areas more users consider off-limits. And users will want to do new things, as the technology moves forward. All this points, inexorably toward the next trip around the loop we've been around so many times.
There's another reason to care. Here's an analogy with hindsight. Suppose you were a home owner in 2005 (I was). All around you are people doing crazy things with mortgages. There's intuitively something wrong about what's going on, it's so diseconomic. Yeah, as it turns out, even if you were being totally conservative about your home investment, you should have been worried. I lost quite a bit of money because I shrugged it off. WTF, everyone else is doing it.