Jerricho and others,
You make some good points but your "dual ATC frequencies are unsafe ...blah blah blah" bandwagon is flawed in its logic.No accident has been directly attributable to this practice.It is possible that in the CDG crash,it was a contributing factor,but this could never be proven.The other crashes you cite are also red herrings.The Dan Air Tenerife was pilot error,the mid-air over Zagreb was controller error.
Why does it continue?Mainly because analysis of past accidents tells us that it is not unsafe to do so.Pilots can not be expected to derive situational awareness by monitoring how controllers are managing traffic flow.Second-guessing a controllers intentions is well nigh impossible in an "English-only" environment.TCAS is always there as a final option in any case.
Some controllers/pilots(I'm thinking Latin America and Africa) can not speak English very well.Conveying something in a short a time as possible can best be done in their native language.Suggest you follow 7777's advice and learn a few relevant phrases(1-36,left,right,cleared line up/land/takeoff)in French and Spanish..that 's if you think you know better than the controller....