Reading the conclusion, they say discoverability of the sidebar is a factor. Well, I've seen some iphone/ipad apps that by default, show all the toolbars and buttons for a few seconds before hiding them (like showing and hiding the dock in OS X); and some even give a little automated "nudge" imitating an aborted swipe motion to show that there are other screens you can swipe to).
If you do that with an always visible toolbar, you lose precious screen real estate: the top bar can just disappear away as you scroll down (with the always available status bar serving as a direct link to it), a bottom toolbar can not do that (note: I don't know if the toolbar hides on the iPad, it does on the iPhones).
That’s seems to me to be the lazy way out. (Also something Apple would probably never ever do. I can’t think of any setting in any Apple application that radically changes the UI. There are modes, like Aperture’s fullscreen mode but no settings. Their iOS apps have even less settings, if you strip away all the configuration there are probably a few dozen real settings in their Settings app.)
I can't tell if that's sarcasm or not. I hope it it is. I thought downvoting was reserved for the most egregious of comments. For me, that one by mikeryan doesn't count.
