I hate roaming charges as much as anyone, nobody wants to pay 200%+ when they go to France or anywhere else within the EU. That being said, competition at least around here for mobile/3G is extremely healthy, prices have come down year on year and the choice/availability has gone up.
What I fear would happen if this went into force is that many (all?) of the smaller operators would go out of business overnight as they couldn't find a network within all continental european countries who will roam for them at a reasonable price.
Then you'll have Orange/Vodafone/etc who own a lot of the infrastructure across europe leverage that so essentially they're the only competitive player and get to set the prices however they want. They'll sell their subsidiaries roaming at X and their competition roaming at X*1,000.
Just look at the US: Their networks are inter-state, and as a result of having to cover such a large landmass it is almost non competitive. You have three companies controlling the whole country. Prices are extremely high and services/choice is poor.
I'd take what we have now, roaming charges and all, over a three network oligopoly.