Why do massages feel good? Even if you just use one of those wooden things on your own back, it feels good. Why?
Here’s my guess as to part of the answer - we all crave touch. We need it. This has been demonstrated amply in many formal and informal versions, including impirical research. So at least one answer must be that it satisfies some very primal desires to be touched, handled, and attended to physically. And while I’m sure there are compelling physiological reasons - loosening up adhesions, increasing circulation, etc. - for me, a massage is a deeply satisfying experience, and I’m willing to say that it is because it feels good to me as a person.