You can create a separate line item which has a lesser value for Child (say 1) and a greater value for parent (say 5) and then apply conditional formatting based on the new line item which you created. You get a result where Children will have a lighter colour and parents a darker colour.(Refer my screen shot)
You can even try using 3- colour scale in conditional formatting and achieve different colours for parent and child.
It is not possible to see the list as tree view in column. But one thing I can think off to differentiate between parent and child is by having some prefix in the list itself. But by doing do, will have impact on the mapping of existing metadata load.
If you have no formula on the members in the module(as per your screenshot), then you can easily differentiate by blue(child) and black(parent) color.
I mean adding some key words before the member name in the list. For example, in your screenshot you can rename the north east as AR-Northeast and so AR-New York, AR-Mid-Atlantic, ZN-US East. Where AR means a short form of area and ZN means a short form of Zone.
This is one of the simple work around which works globally across your model. In this way, you can differentiate the parent and child across all the modules just by changing once in the list. But your customer/users should be comfortable on the naming conventions.