There's an investigation currently going on into the rip-off charges resulting from overseas use of mobile phones at the moment, so perhaps we'll see such things having to change soon....
Nowadays I only use VMC as a last resort - although it's quite handy for sending sms. W-LAN is far, far better.
And as for Vodafone trying to push their 3G VMC card, as they say, YGBSM!!! The GPRS card is expensive enough, heavens knows what 3G would cost!