I grew up in Winnipeg and was 12-years-old when he signed with the WHA Jets. I met him numerous times, and probably have over a dozen of his autographs to this day. He was never less than a gracious, happy guy with children, and never...EVER...turned down an autograph request. The best ambassador hockey has ever had, during his playing days. And the line of Hedberg-Hull-Nilsson is still, to this day, the best line I've ever seen. Glen Sather and the '80s Edmonton Oilers admitted publicly that they were the influences of those great Oiler teams.
If not for Bobby Hull, no WHA. If not for the WHA, no teams, ever, in Winnipeg, Edmonton, probably Calgary and Ottawa, Carolina (New England Whalers WHA), Colorado (Quebec Nordiques WHA), Arizona (Winnipeg Jets WHA), and possibly the entire southern US; at minimum, it would have happened years later.
Also, the WHA Jets had 12 Europeans at one time, when no other team (Toronto) had more than two, so that's another thing that started with Hull's influence.
Not the greatest player of all time, not nearly, but very possibly the most influential to what the game has become.