... and you loose control over all the data. I still cannot understand why so many companies want to store vital data outside of their server rooms just because they cannot hire the right boys to guard them. Every single file you are not able to control can compromise your business one day. Remember, there are dozens of organizations which could be interested in all that stuff. It is simply a bad habit to be too promiscous with all the information one can have in his life.
But yes, as all people use gmail and google docs, nobody seems to care for that anymore. The fact that it worked until today is a good argument that it will work in the future, isn´t it?