Of course I learned about the indirect dowry idea from my mom, especially the part about guests being expected to match the dinner/venue price. But do you remember my dad's drunken justification for spending on a big wedding? (My mom had just raided one of their IRA's for our wedding and he needed a reason not to kill her over it.)
He finally came up with this one -
It was the father-of-the-bride's duty to provide plenty of witnesses to help the groom remember that he got married - so his son-in-law doesn't go out for a newspaper one day and forget to come back.