I've never really looked at this as being biblically approved before, Skully, but why would this have been allowed, and should it still be allowed today?
Well, in my opinion, the Bible was written by (and the god of the Bible was created by) a group of people who engaged in these practices. Their god usually turned a blind eye to these practices, particularly where it concerned the so-called "heroes" of the Bible (King David, Solomon, etc), but often exacted the harshest punishment for common folks who engaged in "immorality". The culture at the time considered women to be nothing more than chattel - property to be exchanged between men in return for goods and services and privileges. To me, it's nothing more than a commentary on the cultural attitudes and behaviours that existed in those times. My personal feeling is that "man created gods in his own image".
Even "Jehovah" - in causing the virgin Mary to become pregnant with His Only Begotten Son™ - disregarded his own laws on fornication and adultery, because Mary was already betrothed to Joseph at the time of the conception. I seem to remember the WTS publishing something to the effect that Mary may have been only 13-15 years of age at the time of Jesus' birth, so it seems to me that the culture of the time thought nothing of older men in their 30s having sexual relationships with little girls.
I'm not saying at all that this is OK, I'm just saying that this is a reflection of the culture at the time the Bible was written, so it shouldn't come as a surprise that certain people who hold the Bible up as a standard of moral and ethical rightness, can also use it to rationalize and justify behaviour that we consider heinous, immoral and reprehensible by 21st century standards.
The Bible, when I started to read it without the JW/fundamentalist awe-factor engaged and see that it's crammed full with paternalistic, misogynistic, abusive stories of how God's Chosen People™ did all kinds of lousy things with God's favour and blessing, I started to realize that it is really not worthy of being held up as an acceptable standard of behaviour. I know a lot of people will disagree with me on that point, but that's just how I feel about it.