If loads of people want it and are asking for it via MS support tickets and via their Microsoft business liaisons I'm sure it will be introduced in the near future.
Features don't implement themselves. I'm sure VBA macros in an editable document is on the list of things that those developers need and want to implement. I'm just not sure it's very high on that list.
If there's genuine business demand, a couple of CTOs phoning MS and say that they'd move to WP in their business fleet "if only documents with VBA macros were editable" might shift it up a few places in the list.
But my suspicion is that like a lot of features "demanded" on the interwebs, there's a fairly limited set of people that really want this feature, and a fairly large number of people that want the features higher up the list.