PUM Question: Is there a reason the 'Copying Update Project' is now split into 3 Parts?

I was wondering about the rationalization for now splitting the 'Copying Update Project' step into 3 separate parts (essentially migrating specific object types in a certain order).  Is there a reason for this?  Would there potentially be an issue if the change package project was migrated as a whole project in one step to move to subsequent test/production environments after the initial application to Dev?

Thanks,

Sean