A database is simply a container of information. One might compare it to a file cabinet. Most people keep their filing cabinets inside their home or office. A public facing database is like leaving your filing cabinet outside in the parking lot. Not usually a good idea, now think of encryption as the lock on your filing cabinet. If you have your filing cabinet inside of your office and do not lock it, you are probably ok (No you are not). Well unless someone breaks in (Hacks in).
An unsecured database that is public facing is akin to leaving an unlocked filing cabinet outside in your company’s parking lot, and oh yeah it is filled with your entire company’s financials. CNET did a nice article on some of the unforeseen consequences of deploying clouds technology without proper security considerations. CNET Article