If your audio speakers are lacking something and you have to use tone controls to get a sound that you like then probably your electronics are not doing the job.
It's not about the electronics not doing their job; it's simply the realities of recordings and living environments. My Vandersteen speakers have level controls in back to help adapt them to different listening rooms, and my preamp has tone controls to further help with specific recordings or living factors.
1. I now live in an apartment and, out of respect for my neighbors, simply can't listen at the volumes I did when owning a house, especially since I enjoy listening fairly early in the morning. As the work by Fletcher and Munson shows, this significantly changes how I hear the music. I don't have a loudness contour circuit, but the tone controls let me recover a well-balanced sound at the lower volumes I often listen to.
2. When I've had a television in the system and watched action movies, I'd turn the bass control down so that explosions, car crashes, etc., wouldn't have excessive impact and again bother the neighbors. The tone controls on my preamp seem to affect just the frequency extremes, so most of the musical score and vocal quality are unaffected.
3. I have some albums that have an overly aggressive, to my ears, high end; tone controls let me enjoy these records much more than I had previously.
4. When I need a more aggressive equalization, such as for muffled, overly chesty voices on some old-time radio shows or poorly recorded conference lecturers, I play the cd's through my computer (the audio output of which is routed to my stereo system) with a program like Real Player that has a good equalizer system.
