A lot of oil flows through the strait from the oil fields behind it. Iran can use the oil without it because they’re behind it. By limiting access to the strait, they can harm the global economy, at least as long as, one, they control the strait, and two, the global economy depends on oil. The Americans are doubling down on their reliance on oil, probably to justify fighting Iran for the strait. So they challenge Iran’s control of the strait. The other option is to make a rival strait, or canal (e.g. Panama Canal), on land the US or an ally controls. That’s expensive though, and will take time, and the US/the west doesn’t really have friends over there, just unsteady allies.

So right now the issue is Iran keeps flip-flopping on letting ships travel through the strait, but I don’t imagine the US would be a better steward of it. The better option by far would be to get the west on renewable energy. If the US/the west didn’t need oil, the Middle East/OPEC would lose a LOT of influence over the global economy. The US may be doubling down on oil to appease their allies in Saudi Arabia.