People don't print documents for fun. They print them because they really need them. Examples of such documents would be reports. If people don't need them, they won't print them.
I don't understand this WWF format because, yes, it stops people from printing documents, but if people REALLY need that document, they would still print it. If they do not need it, they won't print it obviously. This can be done with other document format such as pdf and doc. What's more, they provide the PRINT button, which is an added bonus unlike this WWF format.
To conclude, people won't use this thing, because they can stop printing their documents on other document processor as well. The deciding factor lies in whether they want it of not.