If we had a primarily agrarian society, and there were no slaves, because Torah laws of slavery are completely different than Western barbaric slavery, then all of this makes sense. A farm can't run with two adults with low life expectancy and 2.2 kids. That's how you starve.

Also, and this is no excuse, but if you put a rather strict prohibition (although it is not a Torah law) against, 'spilling one's seed' on the ground, and couple this with what are two completely different biological clocks (male and female), then you get a recipe for some craziness--which no doubt occurs. Why? Because the Torah is also clear that sex should be mutually consentual--and just to make sure it is, the minhag is for married couples to have frequent sex--just to try to get these different clocks in sync. Of course, it doesn't always happen. I'm just saying, as I frequently do, that we have issues to solve.