You should read Founders at Work and Steve Jobs. Both paint pictures of Woz as the guy who quite literally designed and built the Apple I and Apple II (although not quite as much as Apple I), off of which the company was built. Without Woz, there is not Apple. There is not technology elements to unify without him. He is not a dime a dozen.
Secondly, engineers are a dime a dozen. I am one and have met hundreds over my lifetime. The really key people in business and most rare are those that can unify the business, marketing, design and technology elements together in a way that doesn't suck.