Disc brakes safety

I saw this comment:

"Why aren't all disk brake rotors made with rounded edges...?" ~ Kevlar

From - http://www.cyclingnews.com/news/compton-injured-by-disc-brake-rotor-in-lille/#disqus_thread

Very good point and it would be very easy for anyone to take the edge(s) off with a file providing of course that the rotors are just...round.

Did manufacturers drop this idea or are their rounded edges to subtle to make a difference as far as safety goes?

Forgive me if this has been disc-ussed ;) already, a search showed nadda.
Jul 17, 2009
At no point in a cyclocross race is a wheel turning revs enough to cause harm. It has been discussed at nausea in the road section however