How is that a bad thing? If there is anything good in the (still ongoing) monopolization of the OS market it is exactly that. Being able to sit down in front of a device and recognize a familiar user interface and thus being able to pick up the operation of said device relatively quickly is something that is almost universally lauded.
One of the few ways one could complain about something like this is, if your usefulness relies on other people not being able to operate the device you are basing your livelihood on and that would be a pretty weak argument.
Having worked with machines that were so completely different that you basically had to start from scratch to do exactly the same thing has always been a pain in the arse.
I agree with you (but disagree a bit or more, in another sense).
I agree with you, that as a usable tool. Having, consistency, between different computers (PCs), is a very good thing. It means people can write software for these devices. People can get familiar, with the sorts of user interfaces, and hence they can be very productive and efficient.
EDIT: But on the other hand, Windows10 and some other stuff, don't seem to be good things as such. I wish there was decent completion on the Operating System front, so that us users, could buy a decent/useful/sensibly-priced PC operating system. There are Linux's/MACos/Android and stuff, so it is not that bad a situation.
But what I meant, was from a point of view of having fun with computers, enjoying and admiring all the flashing lights, and whirring tape drives, on older machines. They are almost a sort of artwork, very appreciated, by at least myself, and probably other people, perhaps with similar interests, especially.
Analogy:
If you want a powerful, modern, available, cheap, tiny, mosfet transistor, you can buy whole reels with thousands of surface mount ones, on a reel, ready to solder paste onto you own PCBs, with pick and place machines or by hand.
But if you want a large collection of Transistors and Valves/Tubes, going back to early last century, for your own collection (small, private museum). You want to obtain, a wide range of large (through hole), transistors/valves, produced in quantity over the years. They will come a wide variety of packages, and sizes.
Which you can then mess with, look at, and put on display, for your own amusement.
You could, instead, buy a x3000 reel of surface mount transistors, for perhaps £20/$30. Then put just that up, on display. But I argue, that reel, would be considerably less interesting.
tl;dr
It is NOT a bad thing, it is a good thing for most purposes, except for enjoying the immense variety, types and operations, of computers, over the years.