And whether or not LOB apps are involved, people like what they're used to, and they're very used to Windows. The DNA chain between the versions is clear, and Office being Office, it's really become the de facto standard office suite.
I've used Linux. I was once a programmer-analyst in a Unix environment. I love Unix and Linux, but it is not nearly so easy a transition from Windows to Linux as some suppose, just as it's not an easy transition from Windows to a Mac (and all of this applies vice versa, too). There are just so many things we are no longer even conscious of that become almost automatic, like breathing, that we've learned how to do under any ecosystem that must be relearned, and that's just the OS. When you start throwing in alternative applications in, things become even more complicated.
As much as I like Linux, and as widespread as its use has become in data centers, I don't think its day is ever coming in the desktop environment more broadly. The fact that there are God-knows-how-many distros and users have no informed way of sifting among them makes things even worse.