As previously stated by fellow MR members, it just may be a move to entice the windows crowd into a "cheaper" tablet (iPad starts at 200 USD less than the cheaper surface pro 4, never mind the extra features of the SP4, just talking price here), which is a really smart move.
Somehow it brings back memories of when I was on elementary school back in 2002. You see, my father was ready to replace our aging PC (really aging, had the thing since 1995 or so) with something newer; when asked for advice I said we should get one of those sexy and newly released iMac G4´s, the design would allow us to save a ton of space (pc towers and monitors back then as many remember were humongous) and provide us with a more than decent computer; in the end I was not able to convince my father, since OSX (at least back then) was not compatible with many apps or programs, so we ended up getting a generic PC that lasted for quite a while (at least till 2010).
Why mention this?, well, it´s because I think situations like this are part of the reasoning behind offering office at checkout. So as to entice customers into believing any iPad can replace their PC, or at least replace it on mobile situations; IMO, this is true for a great majority of people, however there is also a great deal of people that have many needs above the basic functions of iOS; I for one need a file system, plug in support and many other things; for me an iPad will never be more than a media consumption device (AND also an excellent note taking complement).