Hah! Thanks, Gustavo! You want to know the funny thing? That has actually been there since mid-last year, but pretty much hidden. I was hoping I could integrate it into IntelliJ's first-class option for the Project View, but turns out that's not possible so I just piggy-backed on the existing
Show Excluded Files option:

Of course, no one knew about it, I didn't document it, and the default was to show those files, so the option might as well not have been there. I finally decided to make it 1) the default behavior; and 2) more easily found/configured. It's amazing how much of a difference it makes in tidying up the Project View!
Thanks again and best regards,
Scott