If Microsoft were to "delete and start again" on two areas, for me it would have to be Windows' Search and the Printer stack. They're almost impressive in their terribleness. I literally use Notepad++'s file search for file content and FileLocator Pro for filenames instead of Windows search because it is more consistent, reliable, and faster.
I actually had a conversation with a Microsoft employee at a conference who then worked on search in Windows 7. And after that conversation I absolutely understood why it was in the state that it was in. He believed it was bad because it wasn't complex enough, wanting to pile in even more supported file type filters and expanding language services. Both of which they wound up doing in Windows 8, making it even more complicated and unreliable.
I've given up using it. A work colleague recommended Agent Ransack and I've been happily using that ever since.
At least on this point I'll have to anecdotally disagree. I've been on 10 for more than a year now and I haven't suffered even a single forced reboot. Sometimes the OS notifies me of impending restarts, but they're always hours away so I have time to finish my work. It is, IME at least, more stable than all previous versions of Windows.
- start menu completely random. Like typing "upd" doesn't display anything but typing "update" shows windows update. And the behaviour doesn't seem to be stable. Sometimes old control panels show, sometimes not. Seems to be erratic through time and across different machines.
- microsoft dropping unwanted apps regularly in the start menu. Candy crunch, all sort of ads for sponsored software
- Frequent forced reboots
- Microsoft trying to force my hand on everything. Like default apps, making it difficult to change the default or for videos and images requiring me to confirm on every single different file extension one by one, or not allowing to select an app by its file path for all images or videos (only allowing me to pick from a shortlist of useless apps), making it difficult to create local accounts, all these multiple opt out confirmations are annoying. No means no.
- telemetry
- two control panels and making things worse, settings progressively moving between the two such that the location of a setting is unpredictable. The new control panel often gives the feeling of having been simplified (which in itself is fine) but also to hide the access to more advanced options (not fine).
- generally speaking the big buttons, all grey UI is not particularly pleasant
- many small usability features. Like when prompting for credentials, the RDP client doesn't allow you to access the username and password boxes with the keyboard, you have to select them with your mouse. It feels unfinished.
- I haven't had blue screen for a long time on windows 7, while it has become quite common on windows 10
- repeated interruptions. The OS should be discreet and not be interrupting your workflow unnecessarily. They since removed the full screen notifications in windows 10, but didn't for Windows Server 2016.
There are notable improvements too. Like finally being able to copy-paste in command lines was long overdue. The server features are also much better (hyper-v, powershell functionalities, IIS, etc). But on balance I think it provides a poor experience. I am not saying Windows 7 is perfect either, it comes with its own annoyances but I think it's not as bad.