Having discussed this with people who use MS Office, I can say the key point is this:

Libreoffices UI is DIFFERENT to Microsoft Office.

Thats the real impediment. I have applied "make it more like that" changes including font uploads. It's good. But it doesn't get over the user "principle of least astonishment" which is what drives the resistance.

There is a similar problem with the UI differences on OSX. otherwise rational people find the experience of moving to Office on OSX too hard.

(happy MS Office user on OSX, tolerably happy Libreoffice user on OSX and other platforms)