[Gwathagor]

I believe, Lalwende and Bethberry, that you are letting your strong dislike of Lewis's curmudgeonly tendencies overwhelm and misdirect your understanding of this particular part of TLB.

The point of the lipstick and invitations bit isn't to condemn the proper use of those things, but rather the deeper problem Susan has, of which the abuse of said items is merely the symptom. This makes a great deal of sense considering the context of the previous books: the apparent childishness of Narnia contrasted with a false, silly grown-upishness. This is a contrast that is made fairly regularly throughout the series (Edmund vs. Pevensies, Peter vs. Lucy in "Prince Caspian", Susan vs. Siblings, etc.)