Originally Posted by Chip

Blue-Oval-Base, you'll find a lot of amps internally have a cap in them to smooth the input, I agree that its not something that should be needed in an ideal world, but they are often a useful addition in a car that runs a battery at the opposite end of the car and only moderate sized wiring.
There are other solutions such as the alternator and wiring upgrade that you mention, but they arent just a gimmick IMHO, especially for things like dance musing where the requirements are punchy by nature so time for the cap to recover between notes.
For a long held bass note though, i agree they are totally useless.