I don't know who did that or why, but under AOLserver 3.3.1, it fails to find the URL. Is there a reason to keep these links without extensions?
I beleive the reason for leaving off the extensions is to abstract away the mechanism by which you are serving pages, be it html, tcl, adp, or whatever. Therefore when you redesign your site using new technology you don't break your links since .tcl isn't hardcoded. The ACS request processor - see the doc pages - is supposed to figure out what page to serve. At least this is how it worked back in Sept. Back then in the config file you specified what extensions to try and in what order.
hope this helps