This has been bothering me some time, so I added a base directory strict to my dev blog, which works well. And was the first thing to have when cleaning up my ML!
I wanted to make a strict filter next, so a user can choose to have a directory selected strict or not. This would issue other questions, where to place this, for example. But now, that I have cleaned up the root, I recognized, it would (maybe) be nice to have the selection set strict to all per default. This while:
If you have a clean directory structure there is no need to have this fallthrough mode at all.
(I know the argument a changed behaviour will/could confuse users. This is the nature of such things.)

What do you think and what do you prefer. Give us/me some more input, please.