I don't see any reason NOT to install them, but I can't imagine it changing the results of an engine fire a whole lot.

For boats, it's a bit of a different beast. the cowls for those things are usually huge and hard to remove while on the water. The engine bays are also quote enclosed so there's no ground beneath to feed air to the fire. If you have a fire on a boat, it's often a life-or-death situation, so being able to put the fire out quickly is a huge advantage.

All that said, it certainly can't hurt to have one and I wouldn't have any sort of gripe if I saw them on a competitors car, unless there were a dozen dimpling the hood like golf balls.