One way to achieve greater simplicity is to negotiate for fewer/simpler requirements for the first revision. There's often a core set of functionality that can be implemented correctly in a simpler way, and that gets the work done. Once that's in place it's interesting to see how often people lose interest in what were "hard" requirements before. It's also common that new asks have little to no resemblance to those unimplemented features, and are instead things that they found out they needed after using the new system.
One way to achieve greater simplicity is to negotiate for fewer/simpler requirements for the first revision. There's often a core set of functionality that can be implemented correctly in a simpler way, and that gets the work done. Once that's in place it's interesting to see how often people lose interest in what were "hard" requirements before. It's also common that new asks have little to no resemblance to those unimplemented features, and are instead things that they found out they needed after using the new system.