I like how most of the blame is focused on the bosses, who are actually the ones instilling the disengagement by not engaging. Administrative level superiors have never asked me how things are going, whether I like my job, the good parts and the bad parts, what I need to do it better, etc. They rearrange things and give directions, but they seem disinterested in what the people who actually produce the goods/services do, whether they are satisfied or not, etc. They have no interest in me; it's not surprising that most people have no interest (engagement) in the work/company.
p.s. I like the ideas in Flow, though, and I try to enjoy my work for intrinsic reasons.