It's a standard in Windows that folders have a folder icon. I find it confusing that Start Menu X gives folders the icon of a random item within that folder. Standard folder icons makes it easier to identify folders compared to shortcuts.
I would also like to point out that some of these custom icons make no sense. Why is the icon for the Accessories folder a bluetooth icon? Just because Bluetooth File Transfer is in that folder doesn't make it's icon a good representation of what's in that folder.
Just use the standard Windows icons. They work well. Or give us the option to choose the standard icons or the custom ones.