I am not arguing about NT 3.1, but what inconsistencies were there in Win7 UI?
Starting with Win8 you have basically a random choice if some setting is set in "classic style" or new fancy "settings" dialogs. You can have all the performance in the world if your users spend most of the time just looking for the right place to do something.
Windows 7 has basically the same problem with settings. You have the dumbed-down, XP-style control panel that doesn't expose all the settings, and the hidden classic versions of the settings.
For example, the useless user settings in the control panel and the more useful old version in "control userpasswords2".
oh, OK - I entirely forgot about this :). But it's still just an easily modifiable default for beginners that power user doesn't have to use (or indeed remember in my case :)).
In Windows 10 you have two different kinds of UI and settings that can be changed in one but can't be changed in the other and vice versa.
Starting with Win8 you have basically a random choice if some setting is set in "classic style" or new fancy "settings" dialogs. You can have all the performance in the world if your users spend most of the time just looking for the right place to do something.