There is a strong center-left consensus that more dense construction, in the abstract, is good for society. Most obviously, dense construction is more energy-efficient, discourages the many negative environmental effects of driving, and a new housing unit in Belltown is more or less one fewer unit cut out of forest or farmland.
Furthermore, there are huge non-environmental benefits. The associated transportation choices are good for public health. Although individual projects may result in short-term displacement, provision of affordable housing in the long-term aggregate requires increasing supply. More residents place the city in a better fiscal position and new businesses create jobs. And finally, self-identified progressives must realize that increasing the electoral power of cities is good for the liberal project at all levels of government.
Against the enormous weight of these benefits lie a small series of objective concerns: more competition for parking in City-owned right of way, more neighborhood traffic congestion, more low-income housing, and in some cases reduced property values. Residents aren’t crazy to fear and oppose these changes to the status quo, but density advocates are right to dismiss these concerns as either wrongheaded, or inevitable given that we will follow the imperative to put density somewhere. And if climate change, affordable housing, runoff, health care costs, and/or defeating Republicans* are top-level issues for you then that imperative is clear.