However, how I interpret that statement is that it is ill-advised to over-estimate the general computer user's ability to adapt to changes, or the way 'little' changes end up disrupting the way they interact with the OS.
I might be interpreting OP's statement with my own bias, or reading into it too much, and we could probably go back and forth on semantics all day.
Regarding the control panel, I think the search functionality, which again a lot of non-techies may not even realize is an option, is the main redeeming quality and makes it much less aggravating to work with.
I agree that it is dangerous to overestimate the general user's ability to adapt to changes. Microsoft does a lot of focus groups for this very reason. I don't think that Microsoft can cripple itself by never changing the interface, though. Maintaining an identical interface might work for a while, but eventually competitors who weren't afraid to innovate on the UI would win.
I agree about the control panel as well. Search fixes a lot of the issues. I'm glad Windows 8 has kept search working (and arguably improved it).