Ok - so lets see how these figures transfer:
"if there is a 22% loss in navigational efficiency" - which comes down to time taken to perform various tasks. This doesn't say this results in a task not being completed. Just taking longer. So even if we then pick another figure out of the air -
"then yes, revenue on things like ad-clicking or purchasing may very well drop in the billions." How? It may, but equally you can say it may not. So we are no clearer. Or rather, I don't think we are.
"There is a difference between calling BS on some made up marketing numbers and just being cantankerous for no particular reason. The UI-expertise commentards already called you out on your dismissal due to methodology and sample size."
You think they did, but my comment was based on the leap between this study of 71 users then being extrapolated to a comment referring to billions. Not that you can't get any meaning stats on a UI from 71 users. UI expert I am not, but I *do* know you can design a good UI without and with 3d indicators. So throwing a figure of 22% navigational effiency change based on using 3d or not, I am sorry, but I find it very hard to believe you can then say Flat UI is results in lost billions. This is not a scientific methodology. A flat UI vs a 3d UI - these are VERY large areas. To start talking about Metro and OS design based on this study is a little disingenious. I feel.
"Glibness <> insight." True. Forgive my glibness. However, there is a trend to make sweeping statements based on 'marketing style evidence'. I think this is one of them. Admittedly, this is my thought process. Others will disagree.
Overall what we are talking about, potentially, is just being clear on what is and isn't a link on a web page. What is and isn't clickable on an app. This *can* be done with 3d, but equally can be done in a flat way.
Edit: Something bugging me. You put: "1-2% of very big numbers in the triple digits range of $ billions" may very well equate to "billions in lost revenue", which looks like a quote but I am struggling to see where that quote came from? Trying to work out how 1% came into this.