FWIW, I agree with daveman a bit here... It has often bothered me since the change was made as well.
I get why the change was made: so that you can quickly select different files one-at-a-time to edit the same tag over and over. The issue isn't that I don't understand how to use it. It is that it screws with my long-ingrained muscle memory because it doesn't match the behavior of any other application with similar editing functionality that I've used. It feels wrong, and so I screw it up constantly.
The other issue is that the problem the functionality is trying to solve is, for me, exceedingly rare. I really, really try to avoid having to individually hand-tag files like that one at a time. When I do, occasionally, the shortcut to save having to re-enable editing of the field when I select a different track in the listing is handy. But, it comes at the cost of everyday confusion when I don't want that behavior, and that's way more frequent than the former case.
So, I wonder if there isn't a better solution. Maybe you can click/do something when opening a tag-field in the AW to "enable" this mode, instead of it being the default? Shift-click to edit and leave open, or something like that?
In any case: it hasn't bothered me enough to really complain about it, up till now, but I agree.