There are many reasons why the public could is popular. MSNBC has a post on how executives hate their jobs just as much as lower level employees.
Execs are just like you: They don't like their jobs, either
By Allison Linn
And, reading about the Power of Habits reminded of a possible reason for the displeasure. The fact that some companies are a civil war.
Then it hit me that the Data Center is the one place that all theses families (internal company teams) need to put their information. What other place other than finance has the whole organization connecting. The finance scenario is actually probably easier as it ultimately a money issue. But, enterprise IT is very complex.
If you accept this difficulty of having everyone get along in enterprise IT which can be wearing and frustrating, then maybe people just want to escape the mental anguish and feuding between groups. The lower costs and better service of a cloud environment like AWS could be the side benefits when the ultimate reason was the frustration dealing with central enterprise IT. If you accept this as a potential reason for why users have gone to the public cloud, they are not going to be satisfied with a private cloud run by the central enterprise IT.