I think neither Sony nor anyone else expected the consumer CPU and GPU industry to evolve so quickly in that time, otherwise they would not have spent hundreds of millions developing anew architecture from scratch. Intel also made the same mistake back then when they tried to reinvent the industry with the new Itanium CPU architecture. Hindsight 20/20.
Those years were indeed wild for tech progress. You bought a new CPU, suddenly two years later you have 64 bit CPUs as the new thing. You then bought a 64 bit CPU to be like the cool kids and suddenly dual core CPUs are all the rage.