AM Radio has an extremely important role in emergency broadcasting, because you can cover a whole continent using just 3-4 broadcasting stations, and it is so easy to demodulate, that you can build completely analog recievers that need no power source (they use the carrier wave as a power source). This also means that AM receivers are very cheap, so in a lot of developing countries the only broadcasts most people can afford, and will reach them are AM.
I think we should keep AM radio around, at least for emergencies.
Also, unfortunately, when HF bandwidth gets freed up, it mostly ends up going to companies that use it for high frequency trading, and not to things where it would benefit the public, like ham radio, or digital broadcasts.
You can do this in VLC, though it’s not very practical. VLC’s equalizer has a preamp slider, it’s just not great if you want to change it all the time.