"Good tweeters can also bring out more detail. Most of us also have hearing loss in higher frequencies."
I have come to the conclusion that until your HF is right the whole spectrum of sound you hear will be off. I don't know how it works but the right HF gets you better bass, snappier drums and percussion even below the crossover point. HF does magic to the whole speaker and until you hear it the first time you have no idea that was what was missing in most setups I have heard.