> Previously you could choose to “never combine” apps so you had one-click access to each document. Now you are required to use two mouse actions to open each.

If you have "foo.txt" and "bar.txt" open in, say, notepad, you get one notepad icon on your taskbar that you click on once to open the list of windows and then once more to actually switch. Previously you could tell windows to never combine the taskbar icons so you'd have two separate icons you could change to in one click.