AS generally has pushed people to the nonstop over the onestop if they have a nonstop in the applicable market. It almost always is less expensive to go SEA-XXX over SEA-PDX-XXX, for instance.

Case in point:

SEA-LAS March 5-11: $69
SEA-PDX-LAS March 5-11: $142

It looks like AS doesn't just hate BLI, they hate SEA too.

Not to mention PDX:

PDX-LAS March 5-11: $93
PDX-SEA-LAS March 5-11: $123

The bottom line is AS doesn't want to fill up flights with cheap connecting traffic through their hubs in SEA/PDX if they can avoid it; they prefer local traffic, even in hubs. So that is why BLI-SEA-LAS is expensive compared to BLI-LAS. AS does not want to be a hub-spoke carrier when there's a nonstop in the market and go "hey, you get a price break if you are willing to take a connection", similar to how the legacies work (taken to extremes, you get the infamous TPA-MIA-JFK-ORD-DFW-SFO-LAX FTer mileage runs instead of nonstop TPA-LAX); they want to fill the P2P flights first.

My guess is that once SFO and LAX are true hubs they will have similar pricing: SEA/PDX-XXX will be less expensive than SEA/PDX-SFO/LAX-XXX for most markets. We'll see if that works for them.