What is very interesting is the number of people who get angry over apps charging essentially anything. I can see disappointment, sure, if you really think you can't afford a particular app, but anger?

Where does the anger come from? What must this user expect out of the app store that asking for remuneration leads to flaming comments in the reviews?

The only things I can figure is that there must be some sort of default assumption of freeness. Does the user believe the apps to be coming from Apple/Google/ATT/Verizon/etc, and feels jilted that they are paying for their service and an "incomplete" device [1]? Or does the user believe the apps to be coming from other users, that apps are no more complex to develop than images are to share on Pinterest? Even that feels like a stretch.

I don't know. Have there been any studies on this? Any insights from experienced app publishers here? I think this is a really important question to answer, because otherwise I don't think we're ever going to properly monetize apps, if there is such a fundamental disconnect between developers and users on how the app ecosystem is viewed.

[1] default builds are pretty underwhelming.