Followup -- see this thread from 2004:
http://www.digipedia.pl/usenet/thread/16496/9413/
Looks like at one point, someone fixed this problem in the way I suggested. But then a user on that thread found directory permissions of 755 too restrictive, which may have gotten the fix removed.
One way to make everyone happy might be to ensure that a newly created directory has permissions of *at least* 755. (Although it's a bit peculiar to handle directories this way when files are standardly 644 ...)
-jason