"2) corporate policy. Many (most?) companies, especially large ones, don't want to use any product if there's no company behind it that can provide support (or if push comes to shove be sued for damages)."
I don't know if you've ever read the EULA that you have to agree with to use Word (or any proprietary software) but it specifically states that Microsoft will NOT be held liable for anything. So, you CAN'T sue them for damages.
As for support, I have never found Microsoft to provide good support for any product.