Geordie613: Ummm… two wives mean double the children (or more because wives can double up with more efficiency, presumably).
Thus, how likely is it that two wives with double the children at least, with the need for bigger houses (and possibly enough room to host multiple in-laws) be more financially efficient? The husband would also need to spend at least some time with each wife, which would reduce his time to learn Torah.
Also women used to die in childbirth way more often, so a second wife was like a back-up-Ema plan. Then again, seven centuries ago women still died in childbirth at higher rates. The one-wife thing was a response to cultural pressures at the time.
I wonder what a Kollel husband would say?