I can see an argument for the default behavior (though I would want the combined info too). But in case you or any other reader doesn’t know, hold option when choosing from the right click (or press cmd-opt-i) to get the “inspector” instead which will give you information about the whole group of files.

And related if you do open a mess of individual info windows, holding option while closing a window will close all windows in an application (note that since the info windows are in the finder, this will close your finder window too)

You mean you didn't want 400 info windows that have to be closed individually?