Although the common engineering reason to become a father is happiness in having a woman, in the Earth's gravity well, who actually tolerates being married to an engineer, the most convincing argument for an engineer to have kids is efficiency.
This was confirmed by my recent post-birth conversation with a fellow engineering bud from Penn State. When I asked him what he thought about fatherhood, his first comment was that he couldn't believe how much time he wasted before children.
From an engineer's perspective, child-induced efficiency occurs in: reduction of TV hours (tv/7) unless you want your kid quoting C.S.I., falling asleep faster (z^4) if sleep is to be had at all, reading dozens of books (12b) in a 9-month window to decide how to be a parent, completing laundry in 1/3 the previous time (t/3) despite the fact that the load doubles (2L) with kid clothes, countless hours of free entertainment (1/E-> 0) by watching your newborn try to find his fist, and handyman skill increasing (12h) to keep the house safe.
But the best part is love growing in your home (3L). Nothing makes life better than that.