it's already (almost) possible but tricky and costly
that's the problem with credit cards. It's hard to have a service with low fees on credit cared transaction, and most players (middlemen..) who wants to get into this business will do it (taking the risk) for money and charge some important fees.

There s even a 'new' service that allow people to buy Bitcoin with Paypal (anoon.co) so i think it will come pretty soon ;)
hopefully not with a 5-10% commission...;)