if you trade inside the Ripple Trade System you do not have to Trust anybody to fulfill his promises.
That's correct, you can try to sell your XRP inside Ripple system, but you'll get paid with BTC IOUs, not real BTCs. So you'll have to figure out how to get it out of the system: gateways, trust and stuff. This is not very straightforward, but if you want to play with Ripple, by all means do so.
What I'm offering is a straightforward buy-in program. You get actual BTC to your wallet real fast.
I agree with you on that, even at first glance this Ripple trade system seems like an attempt to create a central banking system out of the Bitcoin.