I only know of a couple piers in Oregon, but there are several in WA, and yes people fish there.
Jetty fishing, as a couple people have mentioned, is very popular and rewarding. It can be dangerous if you don't know what you're doing, because the breakers can sweep you off if you get too close to the water line.
Primarily people fish for bottom and rock dwelling fish off the jetties, it is very uncommon to fish for water column fish. One reason is that there are stricter restrictions on Salmon and Steelhead in salt water and those are the primary water column swimmers. Typical fish caught are several varieties of rockfish (rock bass but not really a bass), ling cod, greenlings, cabezon, sturgeon and so forth. All very very tasty. Once in a while people catch a halibut, and even more rarely an albacore tuna. While they're mainly fished for off the surf, surf perch are often fished for and caught on the beach side of jetties.
It's not really practical off a jetty, but the few piers Oregon has, mainly in bays, serve as great platforms for crabbing.