It's worth pointing out that for a _large_ number of users, the primary copy/paste flow from a Word document is into another Office application (quite often Outlook).

The end result is that you end up with two common flows:

* The program I'm pasting into is another Office app and supports (roughly) the same formatting, or

* The program I'm pasting into is a very rudimentary text-handling program and will just look for the plain-text version of whatever was copied.

Yes, there are a number of apps that fall into the uncanny valley by trying and failing to parse Office's output, but I suspect for most people this is a huge red herring.

p.s. I'm a Microsoft employee, but I have nothing to do with how Office handles copy/paste. This is just my opinion.