I have a slightly different viewpoint on the subject. I work for a company providing cloud hosting services to our customers.
We set up our customer environments such that they get visibility into the entire VM with full Win and SQL admin rights, no different than if they were running on a physical server. They're free to import/export data, copy off their backup files, replicate/logship/mirror to a DR target, or any other activity that keeps their data safe according to their unique business requirements. And, if the customer leaves they're free to take their data with them.
As with any cloud, sure there are tradeoffs with having your data living in a shared environment. It's a deal-breaker for some companies, a non-issue for others. Being a DBA myself, I certainly understand the aversion around placing your data "out there somewhere", but we do run our own internal databases on our own cloud environment without any problems.
One benefit with cloud that is not always obvious to customers is that we can host hundreds of virtual servers in the same cabinet space as a few dozen physical, and that's a cost savings we can pass on. That makes cloud very attractive.