I Think in general the OneNote app is not adjusted for only keyboard typing.
One of the problem I encounter again and again is using the app on different size screens, while the text boxes retain their last size from the big screen the text will "spill" outside the edge and vice versa It will not use all of the space.
I understand that a lot of people want to work with specific text box sizes. However, it will be very helpful if there would a button (and a key binding!) to automatically resize a text box to screen size, either for a specific text box or for all text boxes in a page.