So stop redesigning your damn UIs!
I know why they do it. That's because if you don't change the UI, it is like you didn't change anything, and people don't feel the need to upgrade. It is important for marketing and therefore I don't expect it to change.
But if you really care about usability, don't change your UIs without a good reason. Also, keep in mind that not every user is a young tech addict, it is hard enough to explain to my grandparents how to use a computer/smartphone without them being thrown off by UI changes. Ok, it may not be where your money is, but that's part of accessibility.