I'm curious to know what they took from W95 to give W2K. I've used NT3.5 and up and I didn't notice any w95 influence, unless you mean start button and desktop.
NT4 was the one that took cues from Windows 95—it took the desktop and start button, but it also took the whole grey UI/widget look. NT 3.5 had the same cheesy look and toy program launcher as Windows 3.1. NT4 was the first good windows version (though Windows 95 was the first to be almost as usable as the classic Mac OS).
As far as I remember Win2k was a refinement of NT4, not the same revolutionary leap as 3.5 to 4 was.
I'm not disagreeing that Windows 95 and Windows NT are completely different OSes. But I do disagree that it is "just" cosmetic—the desktop and forms APIs are the basis for the UI of the whole system. It's like saying Mac OS X -> iOS was just a cosmetic change, since much of the underlying OS and kernel are still the same.
Since Windows 3.1 to Windows XP, the aspect and look of the Font installer tool nearly not has changed. I could say that they keep the old 16 bit tool all time with minor changes.
As far as I remember Win2k was a refinement of NT4, not the same revolutionary leap as 3.5 to 4 was.