OK I'll wade in my my 2 cents.
I'm guessing that rear facing dropouts were a safety feature for track racing so you cannot pull a wheel out with your massive jump, and they wouldn't let you on a track if you had regular droputs anyway. Now unless your name is Reg Harris the chances of pulling a wheel out are pretty slim, actually closer to zero, and I think that every track has bike checkers who check the tightness of your locknuts, well they did when I was riding track. In all my years in this sport I have never seen anyone pull a wheel forwards, so I agree with Mike Barry, rear dropouts are no longer required or useful.
Brian (still own real track bike) Booth
Toronto, Ontario, Canada