Well, Jobs' desire for a small, quiet (fanless) machine drove them to hire Rod Holt, who designed the switching power supply for the Apple ][. Jobs quote from the bio (it's unclear when he said this): "That switching power supply was as revolutionary as the Apple ][ logic board was. Rod doesn't get a lot of credit for this in the history books, but he should. Every computer now uses switching power supplies, and they all rip off Rod's design."
Would the Apple ][ have been as successful without the switching power supply? Hard to say. But even at the Apple ][ stage, Jobs' design sense was making its way into Apple products.
My contention is that they wouldn't have had the switching power supply if not for Jobs' design aesthetic. They would have just used whatever was standard at the time, making the machine bigger and noisier.
Would the Apple ][ have been as successful without the switching power supply? Hard to say. But even at the Apple ][ stage, Jobs' design sense was making its way into Apple products.