I completely agree. My fiancé and I are currently two engaged Americans, and we had a couple conversations about how we envision our wedding ceremony to happen. For the most part, we had very casual viewpoints on marriage (we don't need to make a big deal out of it), but she wanted a ring and I wasn't too hot on giving De Beers more money. She agreed with me, even admitted that it was a silly notion to have a diamond ring, but I can tell it's what she truly wanted.
At the end of the day, I decided to go with the diamond and she really loves it. If I had gotten my way, I would've gone with an alternative like moissanite or a synthetic, but we're both happy with the outcome.
It's good to see that Americans are starting to wake up about wedding culture, but I'm anticipating that it will take a few generations for most people to rid themselves of it. If I purchased an alternative gemstone for my fiancé, her parents would've been upset with me, but if my child wanted to get an alternative gemstone, I would praise them.