Well, not quite. Turns out stacked donuts of solid fuel had a more useful performance profile than other designs. The performance of a solid rocket fuel is a function of the combusting area. As solid fuel combusts, it erodes. If the erosion significantly increases or decreases the area combusting, thrust and chamber pressure change and if this reaches an inconvenient balance the booster might not produce enough thrust during a critical phase in the mission profile, or it might shut down or blow up. However as the 3 exposed faces of the cylindrical segment erode the surface area remains relatively constant and/or predictable so performance can be made optimal for the mission profile (in this case roughly constant thrust until burnout near the end of the gravity turn, with the SSME used to compensate).
The political benefit was just gravy...however we should take notice that a gravy train is needed for the successful funding of a federal project. Thus elevating such consideration to an engineering concern, provision of gravy, HHOS.
Wasn’t the booster fuel material more of a sludge as manufactured, that had to be poured into the casing? They couldn’t pour a 100 foot long tube without cracks or voids with would result in explosive failure, so they had to do smaller segments and stack them.
I don’t know, I read that sometime after the accident.