For most of us motorcyclists it's a big gray area. Most of us refuse to ride without hearing protection (those of us who value our hearing anyway) since ambient noise levels, especially at highway speeds, are significant. Also, studies have shown that road noise contributes to fatigue which is something that affects motorcycle riders a lot more than cage drivers. Couple all that with the idea that "helmet speakers" aren't illegal (as far as I know) and IEMs seem no worse than what a lot of other people are doing anyway. I've been pulled over before wearing IEMs and the officer didn't say a thing about them.