And if indeed a lot of brilliant minds join WP, I won't be surprised if they become a clone of the PAP eventually too.
Human beings are flawed by nature's design. We need checks and balances because any power given to one single entity will be abused, it's just human. If WP becomes a solitary party in charge of Singapore, it will become like PAP a few decades down the road (maybe even shorter). So apart from the driver, you need the vehicle commander by his side to make sure the driver doesn't drive the car into the longkang, and a couple of passengers behind to make the journey more interesting.