Cushion is the protective aspect of a good lather. If you want just slick you could use liquid hand soap for a shave and have a pretty slick layer on your face for shaving, but it wouldn't be very protective. A good soap or cream should provide good cushion. I get cushion from both. To me a good soap or cream needs both slickness and cushion. I've had creams that lacked it and I've had soaps that lacked it. I also have both creams and soaps that provide both cushion and slickness. Cream is soap, it's just softer.
Old Fogie. It's not fer eatin', it's fer lookin' through.