On the radio and at bigger live shows I almost never hear any reason for them. Obvious exceptions being tool, RHCP and mudvayne- but they haven't released anything super trebley in years. Most modern RnB that I've heard seems like a plain ol fullrange with the mids dialled back would do the trick fine for the seven or eight pops in a song. Maybe I'm trebally challenged? Really I've never been in a studio or performed at a level that anyone would consider pro and would like to know if I'm missing something or if tweeters are like sport suspension and low pro tires on midsize fwd sedans- consumers just buy because it seems cool? School me on who uses it in a way that sits in a mix to the music's benefit.