i think my main points are:
“it can happen at any online app”
“your data is not safe in an online app”
As the user market signs up for the various sites and decides where they’ll concentrate their online life, there will be a point in time where the tech. companies will need to concentrate their efforts on keeping users rather than concentrating on new users.
Although IMHO that’s what they should be doing NOW. Cos it costs more to convince new customers to use your service than to keep existing customers.
In my Yahoo Mail case above, a couple of MBs of disk space versus tonnes of new features (read weeks of expensive developer time) to compete with GMail.