These are cultural sites, and are important to native people. They've been important cultural sites long before the army began training there. If the native people want access, they should have it, and in this case, it's pretty limited access and the army seems to be blocking them from even those few periodic windows.
The reason the army shouldn't restrict access to sacred sites in Honolulu is because doing so essentially denies residents of their religious freedom. Many Hawaiians access these spaces to honor their ancestral spirits, particularly those native to Hawaii. It seems clear that the army and political leaders anticipate free-for-all access may cause damage to these sacred sites. As such, there has to be a medium that does not violate rights of citizens while also not harming the sites.
The army needs to protect the sacred sites in Hawaii. It would be a shame if these places were destroyed. There are a lot of people that see the United States as imperialist, and they would be happy to destroy these sites. Out of respect for what the sites stand for they are important to preserve.
As the world is continuing to grow, more and more land is being used to build houses and cities. As the human race gets bigger, the nature around us gets smaller. I think that most people to not care or see the natural beauty around them. These sacred sites mean something to people and have had a large impact on their lives and I think that they should be restricted.