Free Microsoft Office for tablets under 10.1 inches

Microsoft CEO Kirk-Koenigsbauer recently announced that Microsoft will provides free Microsoft Office for “True Mobile devices”. As a “True Mobile Device”, only tablet or other gadget less than 10.1 inches are eligible to receive free Microsoft Office for mobile.

However, tablets with size less than 10 inches usually has lower productivity due to smaller screen size and some tablet does not comes with portable keyboard or stylus. Could it be that Microsoft is planning to pull out in-app purchases after offering free Microsoft Office Mobile that comes with limited function?