thats intersting but not sure if it can explain at all the alleged correlation between anger and depression as expressed through music and "hedonism".
i dont think that's the classic definitiion of pleasure, which is the absence of pain, and the fulfillment of needs. and i'm having a hard time with your definition, because the word kind of becomes meaningless when "pleasure" can be derived from "pain, anger, hunger, unhappiness"? does pleasure only happen when the state of unhappiness is stopped? when you finally eat after being hungry?
i agree with the existence of this "psychic reward" for everything people do, but would add that it can be a lot more complex than simple "pleasure"; and due to the psychological make up of the modern individual, can take very, very convoluted, complex and contradictory forms,
i think people engage in activities for reasons other than "pleasure" all the time. reasons like: substitution, replacement, validation, affirmation, compulsion, addiction, release, etc, etc.
a child abuser doesn't necessarily, or just do it out of "pleasure" alone, but a compulsion to repeat what has been done to him/her, and to release some of the pain and anguish bestowed upon their own childhood by giving it to someone else.
a lonely old woman has 15 cats and talks to them constantly: they are not exactly a source of "simple pleasure" as much as a replacement for what she actually wants, the actual source of pleasure of which she is deprived.
sure one can claim that some of these things i've described (the cats) belong in a broad definition of "Pleasure", but with these situations i am saying it is useful to distinguish secondary and problemized forms of "pleasure" from simple and straight forward pleasure.