Kokoro no Sutemi
We practice with the adage "kokoro no sutemi". It is integral to the philosophy at our dojo, pertaining both to kata and randori. Ukemi teaches sutemi at a gross (beginning) level. I think that through the role of uke, the focus on sutemi allows the practitioner to feel the connection between them and their partner, how a particular technique affects them. This translates into a middle level of uke feeling suki (openings) in the connection; the body can feel suki through ukemi, it is aware of suki through sutemi (there is no self and other, only the connected unit). This bleeds over into training as tori, you are fitting into uke's kuzushi ("balance break"), into the suki caused by kuzushi. Improper fitting results in loss of initiative (sente) and kaeshi waza can occur. At the higher levels, I have seen my teachers apply sutemi in many different ways. Some have to do with just relaxing the leading arm enough in koshinage. Just the other day I thought I had one of my teachers wrapped up and was going to foot sweep his butt into next week; without speeding up or applying more strength, they were able to give up and fit into a new relationship that pinned my arm and face firmly to the mat.
This to me was the purpose of "sutemi waza". They are not techniques where you sacrifice yourself by falling to the ground; as a matter of fact, my teachers can do yoko wakare (side separation throw) standing up. They still fall down, they just don't have to fall all the way to the ground.
We do not practice "sacrifice throws" until about nidan level or higher, but on a more subtle level, we practice sutemi waza starting day one.