Do you really think it was just because of the Saints? Two powerhouse NFC teams and the game wasn't decided until the end was the reason for the high ratings. And last year it was because of two powerhouse teams.
That's part of it - it just isn't that it's the Saints. But it is that it's the powerhouse Saints. Other powerhouses don't have the same pull. People like the Saints but more importantly, they like watching the Saints play football. They enjoy watching Brees run the Saints offense with all of those skill players. And there's something attractive about the Saints that the other powerhouses don't have, apart from maybe the Patriots.
I live in another market and people regularly tell me that they really enjoy watching the Saints.