When it comes to urban planning, it seems there has been a long normative discussion about what should be a “proper density”. In this point I take Glaseser 's words as mine:
"Why in the world should there be a 'proper density'?
A good case can be made that cities succeed by offering
a diverse menu of neighborhoods that cater to a wide
range of tastes."
ps. Jane Jacobs wasn't always right.