The problem with that solution is that eaDocX does not know what it needs to print until it opens the diagram, and asks EA for its contents. So you would have to specify the order for each table for each diagram.
But when the contents of the diagram change, perhaps the order would no longer make sense: maybe some items deleted, some more added.
We have thought about this before, but we can’t see how to make it a good user experience.
…but we’ll look at it again for v3.4, as you’re right that it’s a problem worth fixing.