Only supporting grouped taskbar icons is a big inconvenience when actually trying to do work. Instead of clicking directly on the taskbar item which corresponds to the window you want to access it requires that you hover over the icon, then try to pick out the window you want from a very small thumbnail of it. This just adds extra time and unnecessary thought into this process. It's also quite bizarre given that wide monitors are more normal these days with plenty of space to have a long taskbar with many items on it, but instead you only get some short icons in the centre.

This may have been fixed in recent versions where they finally added the ability to change the taskbar grouping in the settings, but I haven't felt the need to test it.

Also the new start menu is a pain in the ass as the quick launch area is just an alphabetic list of applications and/or documents with no ability to group them in any other way. In Windows 10 you can group related applications together and have quick access to "secondary" applications that you might want to use. (I pin "primary" applications to the taskbar and pretty much always have them running anyway). To get to all applications there's another click where as in Windows 10 you just start scrolling as they're just there (maybe that's an option I enabled but it works well).

Those are the two general gripes I have with the new taskbar and start menu in Windows 11. Maybe I'm used to my setup in Windows 10 but I didn't see anything wrong with the way things were from a design perspective. So the change seems kind of arbitrary just to make it look more like OSX rather than from any functional perspective.

One point that I think more technical folks should consider is if we are actively harming our desires to have a functional UI design by disabling telemetry. As that tells the people at Microsoft what features people actually use, and if they only get telemetry from non-power users then they're going to prioritise for them and remove "unused" features that us technical folks use all the time.