Any target curve has to also take into account the particular speaker you're using. For example, rolling off the suggested amount on my already polite Sapphire XLs' tweeters would result in a very unsatisfying treble response. The same for a largish diameter tweeter like an Esotar in a big room; the opposite for a brightish high-midrange/treble like some B&Ws, etc.
When you are eq'ing a speaker with the pink noise and mic you are measuring the response and if it is already naturally, as you say "polite" in the treble then there will be less correction that will be required to achieve the -6dB point (maybe none at all if it is really polite), or whatever you're shooting for. If a tweeter is hot then more eq will need to be applied. The results will be the same no matter what which is the point of eq'ing. You're trying to achieve some sort of desired uniform response. My present speakers require very little eq to achieve my -3dB @ 20kHz target. My previous speakers required a huge amount of attenuation to achieve the same result. Those suckers really were bright!
PLMONROE: The target curves are far from worthless and if you are willing to spend the time to get one locked in, and then perhaps tweaked to taste, you will transform the performance of your system. It is amazing what just a 1dB change at a specific frequency can make. If you don't have your system eq'd you can have the best and most expensive system in the world but not be coming even close to realizing it's potential. Many will say the same about room treatments and that is also true.
And I would never even consider trying to integrate a subwoofer into a system without the ability to eq it.
The BBC dip is a matter of personal taste. I've tried it and I really prefer the sound without it. I thought it took a little presence away. But that is the cool thing about eq'ing is you can tweak to personal taste like seasoning your food with a bit extra salt. There's no rules that say you can't deviate from neutral.
