Seriously, the biggest problem I have always had with tone controls (done well) is that I am too lazy to try to tweak things to perfection all the time. Recordings are too variable to ever even attempt this even if one had the tools. You'd spend all your time tweaking and little listening. I prefer things the other way around.
However, on the occasions I have attempted to tweak sound to perfection using tone controls, signal processors, etc, the results are generally superior to what I started with.