Ginger --
I get where you're coming from, but to offer a counter point? Could it be that the pluckers are just a certain type of personality? For example, I can think of two types:
a) This bird is the bird who LOVES people. He/she wants to be petted because it helps form a bond with the human and makes the bird feel wanted a loved. When the bird is alone or the human is otherwise occupied, the bird becomes distressed, and the distress turns into plucking.
b) This is the bird who plucks for some unknown reason -- but for the plucked bird, who is usually in pain from his/her own touch, kind, gentle hands feel good. Maybe the fact that the bird is missing his or her feathers means touch to the skin is more pleasurable. Or maybe touching them feels like good, natural preening instead of plucking.
Just a thought? I hold to the idea that birds are just as complex psychologically as we are (as I'm sure many, if not most, AA'ers will agree) and these are just some basic ideas based on psychopathology. CC, for example, likes me but she prefers (and is much less stressed) when I leave her alone in her cage to play most of the day. If I take her out too much, she gets agitated, bitey, and sometimes over-preens!