It's four inches of extra pitch, which is substantial. And all the mainline carriers charge hefty fees for extra-legroom economy seating - i.e., UA (E+), DL (Comfort+), and AA (MCE). With AS, you also get priority boarding and an enhanced beverage service. In the context of the current market for domestic air travel, it's a reasonable deal. But if it's it not worth it to you, then don't pay for it.