Not everyone. But it does matter to medium to large businesses. I work at a copany with 35 desktops and 4 servers. There is no way I would recommend purchasing ANY Windows device without a full licence for office.
License compliance is a pain in the butt. However it is worth it. I know that we will not be shut down by a BSA audit because a competetor or former employee would try to convince the BSA that we flagrantly disregard Microsoft's intellectual property rights. Or the rights of Adobe, AutoDesk or Intuit as well.
A completely valid point and one I'd not considered, clearly. I wonder, in these days of BYOD (and appreciating that many Enterprises don't support this approach) how stringently those rules are applied to personal devices. And what is the legal position for the employer if the employee, of their own choice, were to buy an RT device with Outlook on it and use it to connect to a corporate Exchange server?