The old saying of never leaving your bitcoins at an exchange seem to be proven true year after year.
And still people don't bother to change their habits. It has been like that years ago, and it is still so today. MtGox should be the primary example of why storing fund on an exchange is like playing Russian roulette with your funds.
I understand that traders while trading need to have their funds available, but what really makes them look like complete fools, is that a lot of these traders never withdraw anything from their exchange.
It's a combination of them being lazy because they don't want to deal with desktop clients and such, and also the fact that they want to either buy or sell instantly when the opportunity is there. It's convenience over security.
