Again, choice. Anyone can choose to hold BTC if they want. And to speculate, it won't stop there. Yuan could be the next available currency then hopefully more.
I must be missing something, I don't see why having the ability to hold USD, BTC and CNY in one place is a big deal when it's do-able already with exchanges. I'm not trying to irritate you, just trying to understand your point of view on this. So then basically they will be a US based, BTC-e with smartphone apps and a better UI?
Basically, but your account is insured. That's the main thing I'm excited about because other exchanges and services will follow too. It's like Circle is setting the bar up for everyone else to become better.
Edit: And Circle is taking being a Bitcoin financial service more seriously. Seeing that Goldman Sachs lead a 50m USD funding round kinda validates that. It's not like the other exchanges where they get hacked and some of them close. The latest with Bitstamp... The industry is becoming somewhat of a joke because of it. Services like Circle could change that.
If you think keeping large amountd of Bitcoin or fiat somewhere like Bitstamp is a good idea, then I would suggest you think again.
If Circle can insure your account, then you can really use them as a trading account, and do lots of your trades off blockchain, so you won't have to wait for the confirmations during a flash crash or buying/selling opportunity.
That is important for traders, but it is also important for piece of mind. I don't want to feel rushed into trading or moving my money out of exchange accounts as soon as possible due to a chance of being hacked. Circle sounds great to me, the future.