While I agree that when giving a gift, you should respect certain cultural and religious traditions, i.e. no gifting of port or alcohol to muslims, and some of the other examples mentioned, but these two took the cake. They were just rude and entitled.
I also have to say I really hate the old "must give enough to cover your plate" attitude. A wedding is not a fundraiser, and if you can't afford to throw the wedding of your dreams, without the expectation you will "make back" what you paid, in monetary gifts, then you need to scale it back to something you CAN afford.
The brides were rude; yes it may be traditional in some cultures to gift money, but what if you can't afford to gift what would be considered a "decent" amount? In my area, money is given as a gift, but way back when, when I was just out of college, and everyone I knew was getting married, I simply couldn't afford to fork over $100 or more as a gift, so in each and every case, I purchased a nice gift, and all were well received. I tailored each one to the HC, knowing their lifestyle, and what they liked or disliked.
My favorited was someone I knew a little more than casually, but wasn't best friends with. She had picked out cream china with gold trim. I found this lovely, sort of crackled glass serving platter, with a wide, gold band around it. I thought it would coordinate nicely with her china choice. She loved it, and it didn't cost me and arm and a leg either!