Why didn't MS make a MX versions of Word/Excel/etc. like they did for OneNote?
I definitely think it could have happened, especially since they created the radial menu for OneNote MX which seems to be pretty sweet. The advantage of having MX versions of these apps would allow users to still use Word/Excel with total confidence with touch-only input since the current desktop versions can still be tricky to use with fingers (be sure to voice your opinion if you disagree.)
Another awesome video showing the use of the radial menu and input methods in OneNote MX: clicky