This belongs more to FR requests I guess.
I think it's bad to push the burden of doing this on the player (symbolic link in the post above). I was stumped by half an hour and there was no suggestion that it was caused by upper/lower case. "No IWAD found" message is not informative enough. It would be much better if it said, for example, "heretic.wad not found".
Related issue: -iwaddir option doesn't seem to do anything. I have a few source ports and would like to share .WAD's between them. I tried both DOOM2.WAD and doom2.wad, and it still wouldn't find the wad.
(This post is still valid in 1.31)