Running is all about efficiency. Which one is more efficient? Heel strike or forefoot strike? Physics and biomechanics can help us figuring out the answer.
Side note: of course there are athletes who heel strike during running and win competitions. However, for how long can they keep it? Does it affect career longevity? Are they injury free? There are exceptions for everything, but a more efficient athlete will always be a better athlete in the long-term.