There's readily available articles about the leather used in Michael Kors bags and where it comes from.
Luxury brands should cost more because of the quality of materials and workmanship such as hand stitching by artisans. Michael Kors bags are mass produced and the mark up on them is ridiculous. Same with a few other "luxury brands".
For example, why doesn't MK list anywhere the types of movements they use in their watches? Because they're no better quality than the movements found on Chinese eBay shops for $20 most likely.
It's really not in this case. This is very naive thinking. Even high end brands like Hermes for example use questionable methods in the creation of their goods. It doesn't mean you shouldn't buy them if they're what you really want. But know what you're actually funding and don't spread misinformation to others.
Perhaps reading up a bit on how advertising works might shed some light for you on why luxury brands cost more.
Sorry but neither of those links work.
This one does though, and mentions your cotton.