Several reasons:
1) When I was looking to replace my old XP laptop I wanted Windows 7 - but at that time Microsoft only was shipping Windows 8 computers (a few months later they released Windows 7 again, alas it was outside of my time frame). Buying a Mac and installing Windows 7 was the only way for me to go at that time.
2) I do a lot of computer consulting and that includes overseeing the AV/technical aspects of a few conferences each year. My computers are used for several days to supply the feeds to the projectors (I do not own a projector). Every year there is a MD that has his/her presentation in Keynote - as opposed to PowerPoint - BOOM - The same computer natively displays the presentation without issue.
3) When I am in my office I have two, and occasionally three, monitors up and running - I almost always have both Mac and Windows programs open and it is extremely easy to move data between them.
Hope this helps.
It does indeed. Next week, Im buying my first Mac. Being able to run both Office suites is quite appealing..