I was a regular Mac user of Office 2008 and 2011 at my last job for several years as I was able to bring my own computers, various MacBook Pros. I found that Microsoft doesn't give a whole lotta love to their Mac Office suite. Many of us (I'm referring to the Internet community) had to develop workarounds for bugs in the software that have somehow managed to survive several versions of Office along with multiple service packs.
It's not like it's a nightmare to use, don't get me wrong. For general day-to-day document creation it works quite well, but if you get into large or complex documents, you can run into quite a few issues. So, I'm not at all surprised that they don't support Ink on the Mac Office suite.
In the past, there probably simply weren't enough tablet users to justify the effort as Microsoft's initial Tablet PC initiative never gained any traction. Now, with Windows 8, there should be at least a somewhat larger percentage of users that are inking and maybe it will get more attention. Who knows?
I read yesterday that Microsoft lost another $363 million on Surface last quarter, which is it's largest quarterly loss to date. Of course the SP3 wasn't really reflected in those numbers as it came out just before the end of the period. Nonetheless, Microsoft's losses on the Surface now stand at about $1.7 billion, so it's going to take a huge sales increase in order for Microsoft to start breaking even on these things. Time for us to start seriously evangelizing to all of our coworkers, friends, and relatives! ;-)
It may not be quite as big a loss as it seems, though, because Microsoft did axe their Surface Pro Mini, or whatever it was going to be called, at the very last minute and so some of those costs are included in the last quarter's results.
It looks like there is still quite a long way to go until everyday, regular users--particularly business users--begin to make PC-based tablets the norm rather than just a niche product.