maybe because enough of the baby boomers already go to Hamilton Island, and they want to attract the younger ones. I wouldn’t go to Hamilton, personally: it’s too big, too developed, and it’s not even on the reef proper but in the Whitsunday islands, a different geology altogether. there IS coral around the island, but its just isolated bommies rather than a reef with a coral atoll and lagoon affair as one expects from all the publicity photos. the reef itself is a bit further off shore and accessed by seaplane or boat.
if you really want to see the true reef, as in all the dream photos, go to Green Island, or Lizard island. Heron Island is one of the easier ones to get to, as it is at the southern tip of the reef, and it too is a true atoll with lagoon, but its coral is dying off unfortunately.