Microsoft relies on Office piracy as a strange means of price discrimination. The product requires network effects to maintain its near-monopoly position in the corporate world, and having a significant portion of people in "document sharing" networks say, "I don't have Office" is a threat. So, what Microsoft's quietly made decision says to me is that they are worried that a sufficiently large enough portion of computer users were both unwilling to pay for Office and unwilling to bother pirating it.
On Black Friday, many online retailers were running specials on a Home/Student Office "Family Pack" -- three legal installs for $100. This is a midpoint between the corporate price point and free. Perhaps an attempt to introduce another segment? I recall the availability of home/student editions in the past, but the price points were always much higher.