Yours is an extremely important observation. Both Andrew Morrison and I have commented on the relation between shame and hypomania. I wrote about it in Shame and Pride, and there is a good bit about this connection in Knowing Feeling, our most recent book.
If, as I have suggested, the manic phase of this syndrome is characterized by the affect interest-excitement at a far higher intensity than warranted by any situation, then the mere fact that there is so much interest-excitement should make the individual unusually succeptible to impediments to that positive affect, and, therefore to shame. As evidence for the role of the affect i-e, I point to the rapid speech, racing thoughts, and constantly shifting attention that seem so easily explained as derivative of a primary disturbance in the regulation of that one affect. For shame, I always think about the age-old observation that "manics are pleasant and humorous unless thwarted, at which point they get nasty." This is the operation of shame expressed at the attack other pole of the compass of shame. (Sometimes the hypomanic individual exhibits the avoidance pole of the compass, as seen in behavior we used to call "narcissistic.") In the depression that accompanies this syndrome, patients usually say that they are unable to become interested in anything! So I view the entire illness as a biological lesion of one single affect, a lesion that leaves the individual unusually succeptible to shame and anger derived from impediment to that affect.
The far more important part of your question involves the utility of this theory in treatment. The only place I've been able to improve my own treatment of Bipolar patients is my recognition that when they get nasty, they have experienced an impediment to the biologically misdirected interest-excitement. This helps me to remain uninvolved in the interaction, to prevent myself from taking the shaming bait and getting into fights with angry manics.
I began to use Lithium salts with Bipolar patients in 1966, and have remained current with this literature. To the best of my knowledge, my own "series" of patients treated with Lithium and after good control exposed to uncovering psychotherapy may be the longest of anybody in the field. It has been my experience that after about 2 years of biological treatment, these patients begin to be able to learn from their affects just like the rest of the population. When the biological disease is active, there is really very little connection between the affect experienced and the triggering event. People who grow up this way "learn" to pay little attention to their affective life; to the degree that they achieve good control of the illness, they begin to use information derived from affect to build new lives and new relationships. It is not uncommon to see a hypomanic patient, or a chronic bipolar patient make such deep changes in his or her life, and then leave a long term marriage because the partner's difficulty in handling or processing affective information now did not match their own.