Even though I like lipos and own some, the whole idea of adding weight sucks! I am still in favor of picking a Cylindrical cell size and sticking with it. The cylindrical cell provides protection ,heat dissapation and is inspectable.
Granted there are voids in a cylindrical cell pack and the CG may not be the lowest or most compact it set the rules to be fair for everyone.
Many stock races hardly use 2000mah of power, Knowing that a car maker could design a car for a thinner smaller 2500~3000mah LiPo and use lead or tunston placed in key locations of the car/truck to have a most compact CG that anything every seen on the RC market. What they would lack in punch, would come back 10x in corner speed.
By choosing a standardized cell shape it places every chassis and battery importer on the same level playing field. No "1/2" packs, slim or shortie packs. Every chassis would have to accomendate the same size cells, the same volume, and roughly the same mass of batteries. It would be the same concept as the Sub-C battery. Eventhough the weight climbed and the size slighly fluctuated over the years, the sub-c is what it is, a standard size battery.
The bad news for racers is that Lithium cells do not come in sub-c size batteries. But there is a solution, when you combine four 26650 (26mm dia x 65mm L) together you roughly have the same volume and size as a 6-cell Sub-c pack.
The Pandora's box has been opened!