The MtGox issue happened because people keep their wallets online. It's heavily recommended to send the bitcoins from those sites to another account of your own, where you possess the private key.

You have to sum up that now most transactions are fee mandatory, minimum transfer is 5430 sathoshi, and there are dozen of websites whose operation is far from transparent (lot of sites don't display conversion fees publicly, other don't allow you to export your private key, and so on); and is quite troublesome to convert from bitcoin to conventional money, provided that if you want low fees it demands at least some days for bank transfer operation.