I still think that keeping big and prosperous exchange going is more profitable for the owner in the long run.
We need to remember that cryptocurrency phenomena is still a new concept, we don't have laws and rules set.
In the end I expect that exchanges will be no different that current banks, fully regulated, licensed and controlled to certain point.
I supposed a big exchanger should have a very strong security, the case of Mt.Gox I believed got helped by the insider, and of course exchanger is a very profitable business, and I agree one day all of the exchanger will be regulated and need to report all of the data, but I appreciate everyone that created exchanger, crypto currencies can grow this big because of the exchanger, most of the alt coin can survive because people trade the coin from exchanger