The cylindrical wheel decision is closely related to the decision to use Indian/broad gauge, which was expected to provide a smoother ride as well as allowing more support equipment to be mounted under the car where it would produce less vibration.
Both are decisions that have not stood the test of time, although the choice of Indian gauge cannot practically be reversed. But I think the discussion around this often pays the original designers far too little credit: BART was intentionally a highly innovative design with numerous aspects that were somewhat experimental. BART's automated control system, for example, was such a debacle that BART initially operated with signal towers and the control system required nearly complete replacement. But it was a completely trailblazing design, and the same missteps would have to be made somewhere. BART was used once again as a test platform for an innovative radio control scheme in the 2000s, evidence of which can still be seen mounted trackside on the SFO wye.
Many lessons learned from BART's performance have contributed to later designs around the world, including notably the DC Metro which was built just shortly after by some of the same contractors.