"...Iran and other countries were already using lasers to target ships and commercial airliners..."
This sounds an awful lot like the scaremongering that was put out surrounding Iraq and its WMDs. We all know how that turned out.
Laser targeting and guidance systems have been about for decades. These days a simple laser pointer can be considered a laser targeting system. It is a massive technological leap to go from milliwatt laser pointers to 150kW directed energy weapons: a technical leap that Iran, and countries like it, simply are not capable of.
The Navy are clearly banking on the fact that Politicians simply will not know the difference and will just allocate more money to Defence Budgets out of misguided fear. Nevermind that the Navy's own Laser Weapon System's performance has actually been rather lacklustre.
Maybe the Directed Energy Weapons program is yet another area of US Military spending that is deemed 'too big to fail'... just like the F35.