It would be from a financial standpoint. Changing a standard this widely implemented is very costly.

Why change it if they're compatible anyways? Most devices in the eu are designed to accomodate both, its just a question of the earth pin being different.

I've travelled all across europe, coming from a country with the french style outlets. I never had any problems connecting anything except for Switzerland and Italy, because they stuck to their own (inferior) standard thats not compatible with anything else.