Omeed,
You keep writing that the side pane position is the "default" view. I hate to be a stickler for accuracy, but it's actually the ONLY view. Microsoft and the OneNote team have left no other option, hence the "default" descriptor is simply wrong, since it
implies there is some other "non-default" option - which there isn't.
I have moved into an academic position and have been forced to return to using PCs and Microsoft products, and I have to confess, aside from the actual operating system, I have been very pleasantly surprised at many of the software applications.
Now I have just delved into adding OneNote to the mix of possibly useful tools, and I must agree with most posters here - the side nav panes take up WAY too much space to be useful. The supposed fix to hide and reveal the panes repeatedly is
exactly the reason people preferred actual tabs at the top of the screen. That feature allows for quickly selecting another notebook without having to first reveal the nav panes, then select the < icon to open the notebook pane, and
THEN selecting the notebook. So, Microsoft has managed, in the name of "improvement", to make a one step process be "shortened" into three steps. Gee, thanks!
I continue getting reminded by examples when I come to work now why I abandoned Microsoft years ago whenever it was in any way possible. Until the usability of OneNote, which seems to offer truly wonderful features under the hood, becomes, you know, usable,
I'll just have another icon to clear from my tiles.