Years ago, suds DID mean better cleaning performance. Today, because of the advancements in detergent formulas, it isn't really the case anymore.
The idea behind detergent -without- suds is that the formula is 100% in the water that is flowing through the fabrics, not suspended above them or around them, and even worse, stuck to the drum and in the outer tub. It's not doing any good if it's just hanging around not even touching your clothes. The surfactants and conditioners in new detergents are designed to break soils loose and actually surround the fibers of your clothing, as well as surround the dirt molecules so that they cannot reattach. Yes, the soil may not be suspended away from your clothing, but it also has a very difficult time latching back on. Furthermore, the idea of suds in a front-loading machine are very counter-productive when looked at it from that perspective; even if there are suds, the clothes are being rolled through and over the suds, so that dirt is still being folded and tumbled through the dirt that would be "suspended" anyway. The only way suds could be useful in laundry would be in a conventional top-loading machine, where the clothes are moving around under the water and the layer of suds is riding on top, not being mixed back down. My only thoughts when seeing a layer of foam is "look at all that detergent riding on top of the water that COULD be flowing through the fibers of my laundry".
The analogy of suds being required when washing a car is a good one, but keep in mind that your car's surfaces are stationary, and are not porous at all. In that case, yes, the suds are required to keep dirt away from the surface so that they flush away when sprayed off.
To me, a dishwasher is a prime example of why suds will hinder performance. The machine itself cannot perform adequately if suds are present because the air trapped in the bubbles will suffocate the pump. Despite there being no sudsing, dishes come out spotless because the surfactants in the detergent help to break the soil away from the surfaces of your dishes, and coat the dirt molecules so that they cannot reattach. The absence of suds allows the water to drain smoothly off the dishware and also down the tub's surfaces and out of the machine, so that the dishwasher can extract as much as it can before refilling for the rinse. I see this concept being the same for laundry machines. Suds only result in detergent and soil being stuck on the interior surfaces of the machine during the first spin, not to mention the clothes themselves. If the water is properly conditioned with the detergent, the machine can extract and drain more of the actual detergent away itself, leaving much less to require needing rinsed out.
