Many things are different now compared to when the rest of the telescopes went up.
1) In the 80's and 90's Hawaiians went through a cultural renaissance so to speak. Before the 80's there was actually a sense of shame to being Hawaiian associated with bad stereotyping and being known for not having anything. This changed with music, a rebirth of the language, an introduction to Hawaiian culture being taught at the University level, and than charter immersion schools dedicated to Hawaiian education. This resulted in a resurgence of culture and pride.
2) The advent of internet and social media. This offered instantaneous access to masses. Propagation of information (even false information), made it easy to touch a lot of people and stir emotion.
3) When the other telescopes went up there were a few powerful elder community leaders, kupuna, who were really instrumental in communities. By approaching them and getting them on board with the project was a sure-fire way to get something done. When people found out that certain kupuna were on-board, no one would want to oppose their thinking. Sort of "Who are you. You think you know more than Kupuna xxxx."
4) Now that kupuna generation is gone. There's a lot more leaders and beacon's within the community are far and few in-between.
End result is a lot of opposition when before it was only a handful of diehard activists.