"It's usually an out-of-their-depth CIO who's going along with the CEO, who in turn was taken out for a very nice lunch by a bunch of IT or management consultants, and they told the CEO that the cloud was where it was happening, and if his company didn't move there, then competitors would eat his very nice lunch."
I'm sure that helps, but it's usually the vast cost savings that really facilitate moving stuff to cloud based services...Our email and collaboration infrastructure is now effectively free after moving to Office 365 when we consider that a full Office license was included!