I am just a recent grad (still basically a student) but this is what I think…
maybe…???
Interaction designers focus on how services, products and technology can be better for people. They design and empathize with the emotional usage, need and bond that we have with our servies, products and technology.
the value of it is that interaction design can have a more holistic way of approaching design- seeing people as the medium (not bound to any particular material, form or language).
frog’s David Sherwin has a good definition in his presentation “The Language of Interaction”