Exchanges are only needed to buy and sell Bitcoins¹; after that, you can move them out permanently, whereas with CCs, you can never be sure that the merchant didn't record (maliciously or not) your CC info. You also only need to trust one exchange, not N merchants, so it's much easier to do proper evaluation.
¹ Technically, you never actually need an exchange at all, there are other ways of getting Bitcoins.
Exchanges hold most of the hot bitcoins, so, they are a very lucrative target for both external, and internal theft. They definitely need to be regulated. One thing about the exchanges is how greedy they really are for the crappy service they provide. Most stock trading is a fixed fee and all exchanges charge a percentage.
