Or, on *NIX platforms, simply detail a directory for CGI, and leave off the .pl off the file(s) in question. Of course, then one insures to make only the appropriate files executable...

(You can likely do something similar on IIS, although I can't think of how to make it work, off-hand)

Don't really have an opinion about your philosophy; I agree it's a issue (also: knowing what the backend is can lead to Programming Language-specific crack attempts), although it's not the bug-a-boo to me you find it.