Tiger Woods impact can be assessed from his impeccable record and his popularity across the globe. I would say that he has impacted golf much more than Nicklaus, which is apparent by the fact that while only people who are into sports know about Nicklaus; Tiger Woods is, more or less, a household name.
Tiger Woods is a great golfer - I'm not denying this. However, can you really say he had the same impact as Nicklaus did on golf? Of course not. While both of them are great golfers Tiger Wood's adulterous behaivour deterred people from golf and removed a lot of his idolisation while Nicklaus didn't really have a negative effect, for the most part.
Tiger woods was headed in the right direction as Jack Nicklaus but was unable to live up to that standard. He was going in the right direction but could not overcome so hurdles that he had to face later in his career. He could have been legendary and would of changed the outlook on the game, but he didn't. He is still an amazing golfer, but did not do what Jack could.
Tiger Woods should have been the most influential golfers ever. However martial problems and injuries have hurt his legacy. He is no longer dominating and often rather mediocre. He is not a leader but more of a complainer. He will still be known as one of the best golfers ever, but not the best ever.