Putting a nil node is not tricky but rather good maths. Adding manually some space would be ugly.
In pstree you manipulate (ordered) n-ary trees so there is no notion of left or right child node. You can only give a list of child nodes (ordered).
Think of how you will implement binary trees (t := () | (t, t)) with ordered n-ary trees (t := list of trees). The two following binary trees are different.
/ != \
While they are equal as n-ary trees. You need to explicitly encode the skip of the left child node to simulate that in n-ary trees.
The pstree creators proposed you a distinguished
\Tn node (nil node) for that purpose.
Just like when a missing information is an information.