This is the same thing that makes lattes tasty. The microfoam affects the way flavors are perceived in part due to a textural difference which affects how flavors are absorbed.

Foams are a fascinating and not very well understood phase of matter. We only recently started developing mathematical models that can approximate predictions about some kinds of foams, but most of what we know about them just comes from observation. Foams are everywhere, and yet we know relatively little about them.