Because it's more than one issue. For years the GOP has been mostly about guns, gays and God, but that doesn't work up here. There's not much social conservativism to be had and the GOP is going way out of it's way to field people that are popular to the far right, but pretty much repellant to everybody else.
In WA, we don't really have the kind of far right that they do in much of the rest of the country, so it tends to chase them into the hands of the liberals. It's been nearly 20 years since the GOP fielded somebody with any hope of winning the state and they're getting worse and worse. Dole had a chance, but he wasn't different enough from Clinton to get votes. He was also the last Presidential candidate to take the state seriously.