Marriage=slavery?

One of the proofs given to me that Orthodox Judaism is really enlightened was that Jewish marriage guaranteed a wife that her husband provide her with "food, clothing, and marital relations."  These rights are guaranteed in the ketubah signed by every Jewish couple just before they go under the chuppah.  This was usually framed in a very feminist, sex-positive way.  As I like to put it, "On the eighth day, G-d created the orgasm--and it was GOOD!"
Sounds great in theory.  But as usual, context is everything.
This particular list of a wife's rights caught my eye as Queen Mom and I were reading the parsha last Shabbos.  Only it was not in the context of marriage.  It was in the context of buying a slave, or as the text put it, "a Hebrew bondswoman."  Not really much to argue with there.  Apparently, bride purchase was a common practice in the time of the Torah.  And these wives had the status of wives--sort of.  If the master decided not to marry them, they had to be released after six years.  (Sounds like there was a "try before you buy" option.  Nice.)  They also had to be paid off for their betrayal, adding to the theory that these men were "test-driving" their slaves before deciding whether to make them a permanent fixture in the harem.  (And, yes, there were multiples.  That line about food, clothing, and marital relations was the guarantee given to these slaves just in case Massa decided to get himself another slave wife.)
Disturbed enough?  It gets better.  Understand that I use the term "bondwoman" rather loosely.  See, according to the commentary, these "bondwomen" were roughly the same age as my daughters.
I wish I were making this up.
Straight from the commentary of my Stone Chumash, now considered the standard in Orthodoxy, "For example, if she had been sold when she was five years old..." Yuck.  Stop right now.  Put down the book, and back away slowly.  Children?  Seriously?  Grown men are buying CHILDREN for their harem?  This is the Torah?  And, please, spare me the cliché about how children were more mature back then, blah, blah, blah.  This is little more than the permitting of baby rape.
Makes you rethink that immortal line from the ketubah, doesn't it?