Here's a theory: Austen writes about relationships, gossip, social status, etc. She's basically a chick lit author. However, she is also head and shoulders above your average contemporary chick lit author, and she is respected as a literary author. Therefore, women can get whatever they get from chick lit by reading Austen, but by admiring her publicly, they don't face the stigma of enjoying trash.

One problem with this theory is that your average contemporary female reader doesn't actually seem to feel any guilt or shame from reading garbage; see the popularity of YA books among women in their twenties and thirties.