Trust me, they (manufacturers) don't have a choice, the LED business is a rapidly growing semi-conductor business with amazing rates of new product introductions. Every generation is significantly brighter than the last. Older products will be immediately phased out, making place on the production line for newer ones.
I'm guessing these indicator light manufacturers are buying the same LED's all the time, but after a few years the same size / type of LED will be much brighter than the ones used when the original products have been designed.
Maybe this is a niche market, maybe I should start a company making dim LED's especially for the bass amp market!
But joking aside, the amp guys should be able to fix this by useing a lower current to drive these indicator lights, I don't think they will realize it's an issue unless enough of us start to complain.