Don't see the point, other than muscle-flexing. The US already has enough air assets in the area to deal with anything Iran has, and a surface warship in the Straits of Hormuz will just provide a vulnerable target, given that Iran does have submarines. Maybe they just want them for the cruise missiles, but then they'd be better off with several more submarines of their own as those are quiet enough to evade their Iranian counterparts. So imo, it's mostly a show of force.
Now, I could see parking one of the destroyers right next to friendly states in the area for missile protection in case Iran get any ideas, but that doesn't seem to be the plan.