BA:
You said different time/different place. I agree. So that makes culture and time two important contructs to morals. That is why Biblical morals cannot be universal and eternally enforced because times, cultures, and people change. And if God "allowed" it, then He must have accepted it because He was pretty quick to get rid of anything that he didn't like.
Viewed within the context of a middle eastern rural-agrarian society, I would say the set up of multiple wives and brother-in-law marriage, etc... provided a social safety net. This was not something God allowed but were clearly institutions he brought about through legislation. If God was lawgiver, judge, and king and all his activity is perfect, then the laws he gave Israel--- including laws governing slavery, war, concubinage, the spoils of war, genocide---- also are HOLY LAWS because they came directly from Him. To say that God simply permitted these things suggest that we find these things not so holy, not so moral, not so pure within our modern paradigm and have to give God some kind of excuse to let him off the hook ( a hook created by our own human sensibilities.) It is almost as if you are embarrassed by God's actions much like when people make excuses for the bad behavior of others: He didn't mean it he is just having a bad day/She only acts like this when she's sick, etc....
If there is a God and He created all things, then he needs no excuses, no defenders. He can do what He wants, when He wants, how He wants. I just don't have like it.