Because system-disk encryption in software is still relatively new, it probably still has the flavor of something exotic and relatively untested. This isn't far from the truth, especially if you haven't given it a shakedown in your own organization due to questions about the implementation.
However it's put to use, one key truth should always be in mind: disk encryption is not security. Or, rather, disk encryption is not the sum total of security for a system; it's one of many things that can enhance security. Full-disk encryption works best when it's part of a total protocol for the care and handling of a piece of hardware constantly on the go.