That is exactly what the regulations put in place. They don't mandate a price-flat market.

There're safeguards put in to prevent price-flat market situation. And it's damn nice when a day's trip to neighbouring country doesn't mean switching SIM cards or outrageous fees.

Explain that too people where their SIM card switches to the neighbooring countries provider.

And more importantly, surfing while on vacation in the EU ( 100 mb) won't cost you 200 €'s anymore. Some people had a vacation bill of 9.000 € of their provider ( source: newspaper & victim was local politician)

It means more competition, because consumers can choose between effectively any provider in the EU. So if the providers in say Germany have awful deals, you could get a SIM from a company in the UK that has less shitty deals.