People like Gene and others argue that a flat frequency response isn't that good. That it won't sound good, it would produce a boring sound.
You are wrong again!
You absolutely do not want to equalize for flat at the listening position. Music will sound over bright and awful.
Speakers need to be as flat and neutral as you can design and build them, with a nice dispersion pattern and a good step response.
The dispersion is in many ways key. As you move further away from the speaker, then you get an increasing proportion of reflected sound. The reflected sound has a significant reduction in HF compared to the direct sound. So at the listening position the frequency will, and should not be flat. If it is it will sound awful.
There is more to clean sound than flat frequency response. Very flat bass can indeed sound muddy. This comes down to Q. You get a good idea of this from the step response. Low Q speakers have a much more natural and clean bass than high Q ones.
Good speakers have a flat frequency response a good dispersion pattern mirroring the axis response but smoothly falling away at the high frequencies, and a Q of around 0.5 certainly less than 0.7.
Therefore a good speaker with a superior dispersion will have less HF at the listening position and sound superior.