Good question. However, what is also true is that it is women who traditionally want the modern conveniences PLUS the "beautiful" home and in many instances, this cannot be acquired or obtained on a single-income household. Dittos, two cars. Furthermore, preferential affirmative action in many areas includes quotas for women (all ethnicities); quotas for minority males -- but nothing for white males; thereby putting his own marketability and income in a higher risk category.
Also, what is not asked in this survey (and I find curious, or suspect..)? Do daddies want college for their offspring in the same % as mommies do? If so, a second income may be quite necessary. (Given how much college costs; plus how little it delivers in re quality; nonetheless, degrees are still required at most if not many businesses).
RE your post #29 - Very good points you bring up.