who are you going to call when your btc wallet gets hacked for $10,000 of BTC ?
The flip side of
freedom is
responsibility. The traditional banking principles are still in peoples heads when they go into bitcoin. However that is not a good idea.
You yourself are the best person to be looking after it, not someone else. Trust the exchanges with the transaction, not the storage.
Having your wallet in a server, is not any more secure, if anything you've just put a target on it, making it more vulnerable. Trusting others with your money when you are more secure looking after it yourself has also made it less secure, where in traditional banking you can usually expect it to be safer. The problem is the benefits for ease of use has erased many of the security advantages native to the bitcoin protocol, since automation has became so normal it means passwords are floating around and large open wallets can be accessible.
Maybe a year from now, exchanges and e-services based around bitcoin will have proved themselves more secure, however I don't see anything changing right now. I'm much rather look after it myself, knowing I'm responsible for it and I won't be a public target.