The reason given to me by support was that it is to prevent us from upsetting eBay.
Support: "The Paste from Word tool strips out the proprietary MS formatting code that could be objectionable according to eBay."
But WE are paying for this service - not eBay.
But it is nonsense anyway because eBay PERMITS us to paste Word text.
If Auctiva were to give us a proper editor instead of a toy (which has bugs anyway) I wouldn't mind so much.
But Auctiva has actually taken major functionality from us without warning. Worse than that, I was tricked into changed to the bad editor by comments made by support on this forum.