Taking a lesson from mtgox - Wouldnt it make sense that we demand private keys for any money we keep in an exchange, that way ensuring that our BTC is "safe" and under our control?

Also if companies like mtgox and coinbase arent even keeping the btc in the payment address accounts how can we know they have what they say they have!

Apparently they dont even promise that our bitcoins will stay in the addys linked to our accounts

http://i.imgur.com/OPITjzo.png