2. Fujairah is within drone and missile range of a lot of remaining Iranian strike capability.
3. Fujairah is not really equipped with a large amount of high precision, reliable, expensive, slow to procure and replace air defense systems.
4. Fujairah has already been struck repeatedly since this conflict kicked off.
5. The oil pipeline capacity from the 'west' side of the UAE to Fujairah is nowhere near enough to meet demand, even if the port and oil terminal were considered totally safe by ship owners and cargo owners, which it isn't.
https://en.wikipedia.org/wiki/Habshan%E2%80%93Fujairah_oil_p...
But it obviously wasn't designed to carry all the oil going through the Strait.
Do you think people are dumb? Obviously beneficial and easy actions that no one has taken rarely exist in the real world. You're basically suggesting the people actually there who have a better view than you are profoundly stupid.
Can the system run if those above ground areas are destroyed? Of course hypothetically they can be defended. Just like hypothetically a few drones should not be able to shut the world's most powerful navy out of the strait.
In reality we know the real answer lies in an admission of your answer. The best defense is electing governments which will not wantonly engage in armed conflicts.