Everyone keeping their bitcoins in exchanges/(think banks, or broker accounts) instead of their own wallets is completely subverting the point of the idea of bitcoin. BTC has some great unique properties as a p2p cryptocurrency - which goes out the window when everything sits in a few exchanges rather than a bunch of wallets.
One of the problems with ever realizing a "true free market" in bitcoin trading is the time spent waiting for block confirmations. There are barriers to entry in that you can not just transfer your coins to an exchange and sell instantly. Because of this a lot of people who trade bitcoins keep a certain amount in their exchange accounts.