It took me a long time to "get it", too, FiskerZee. Your statements above are perfectly correct in terms of the physics. So, it's really a question of philosophy. Do you want your Karma to be mostly an electric/emission-free car, or do you want your Karma able to operate at it's peak performance levels at all time?
The TOM unit allows you to keep your battery above 60% State Of Charge which is where the Karma accelerates the best (in SPORT mode). So, if you don't care about burning gas, and what you do care about is the best possible feel of acceleration pushing you back in your seat when you pass somebody on the highway, that's where the TOM unit shines. It keeps your battery charged ... at the cost of gasoline/emissions. The TOM unit gives you options to keep the generator turning more often than a stock Karma.
However, I would think a better battery would appeal to a lot us on the other end of the spectrum who drive our Karmas to maximize the electric range and aren't as focused on the G-Forces on our behinds.