As far back as Shakespeare’s day, anyone with a lick of sense knew that cities are the people, not the buildings. Therefore, design of buildings without consideration of people will never be successful design, because the ultimate result will be no people.
Even the federal government, in their "Smart Cities Plan", understands that "cities are first and foremost for people". However, in Seattle city government today, there seems to be a lack of understanding about the importance of people in design and the impact that poor design can have on their lives, their productivity, and even their health.
Yes, relative closeness is part of the urban environment, but does the closeness in a particular design allow enough sunlight and privacy? Residence to residence (24/7) closeness is very different than commercial to residence closeness; and single-family neighborhood closeness is very different, too, because you don't have walls of glass between buildings.
When city leaders make the politically correct “every person matters” statement, and then you propose in effect Robin Hood legislation to solve a lack of affordable housing, you are treading on dangerous ground, The more well-off residents can, with relative ease, walk away from a downtown that they believe is headed for problems and decline because of bad policy decisions.
On the other hand, if you include equivalent development capacity through additional height rather than the additional 1000 sq. ft. per floor of additional girth in new residential development downtown in the HALA legislation, and at the same time include allowances for equivalent square footage in additional height to solve alley congestion and tower separation issues affecting light, air, and privacy [with tower spacing, alley setback, minimum lot size, max lot coverage, etc.], everyone wins.
You will save downtown Seattle for another generation of residents, maintain development capacity for developers, and provide the funding for Affordable Housing.