If you could spin-up a secure VM pre-configured with BitcoinD, up-to-date blockchain, and RESTful interface, is that something you'd be interested in as a service?
Given that the hypervizor has access to basically everything on the VM why on earth would I ever run a wallet on someone else's virtualization layer?
For the same reason people use banks instead of stashing their savings under a mattress. If you're willing to place a little trust in a service to use as the hot wallet (keeping most coins in coin storage), there could other benefits such as:
* speed of deployment
* easy scaling
* easier interface/api to interact with
