Is it not building for density? I've lived in the same spot near capitol hill for 5 years and there are new high-rise and mid-rise condo buildings in every single direction. It's been nuts! They built like crazy.
All the construction is concentrated into a few small pockets. So inside one of those pockets, it feels like a lot. But the majority of Seattle's land is still single-family detached residential only. This is a zoning map, you'll see that the "highrise" and "midrise" pockets are very small:
And those developments have been concentrated in a few areas barely zoned for such. The vast majority of the city is zoned for single family buildings not townhouses/low-rises/mid-rises nevermind NYC-style high-rise apt buildings the city and the young so desperately need.