One consideration in this area is the aging population. Elderly people have a difficult time in two-story homes thus the market for them is a bit smaller.
For non-elderly people, stairs are a PITA. Seems you always need whatever is upstairs. In our remodelling efforts, we have taken great strides to keep our home 1 story.
For me, two-story homes belong on big lots or lots where the land slopes and the house can follow the lay of the land a bit.
A 2-story structure on a small lot just bothers me. It is too imposing and depending on the orientation, can rob the lot of sunlight, expecially when it is between two other small lots, each with their own two-story structures.
This is what I hate about the new construction in San Diego.