Think of how snarled a major city becomes when a single major bridge goes out. Look no further than the FSK bridge in Baltimore and the dramatic effect that one single bridge being down had on that city's ability to move people and goods around in a timely fashion. Adaptations eventually took hold, but they're more expensive and slower and will be until the bridge is repaired.
... and that's just ONE bridge in ONE city.
Now imagine a deliberate and calculated removal of all major spans in every major city across the country, prioritizing the most significant disruptions of traversal for commercial and residential traffic. Think of how that will disrupt the entire country's ability to get literally anything done for months. Militarily and civically.
If you want to paralyze a modern nation state while minimizing direct casualties (knock on ones are a different story), disrupting traffic infrastructure by removing critical spans is a great way to start. Now add disrupting electrical grids and you've just brought every major city in Iran to its knees.
Goods and services will cease. Grocery stores shelves will go bare because Trucks can't get through to areas. Gas stations will go dry for the same reason. People won't be able to get to work because either the only route is gone, or the traffic gridlock is so bad, they've been told to stay home. Emergency services will be cut off from whole areas. Supplies for Iran's war machine will be strangled. Raw steel or munitions components won't be able to move around easily. Neither will any other resources or personnel.
People will adapt eventually, and eventually things will get fixed and rebuilt. But it will take quite some time and a significant amount of resources to do so. But I think the best this administration can hope for is a complete neutering of Iran's ability to function as a modern society for the rest of Trump's term.
How this will alleviate the problem of the Strait, I don't know.