They avoid tangled cables.
The base of the cable is stashed in the neckband, too, which means there’s less material to get tied together. Of course, you can’t fit something like this in your pocket, but still.
They’re basically replacing mono headsets.
Since it’s not going in your pocket, the idea is to keep the neckband on at all times. If you’re the kind of Busy Important Person who’d wear a dedicated chat headset, this lets you toss in an earbud when someone calls, then switch over to music, or just leave the buds hanging off your chest, when you’re done.
They make it easier to implement noise cancelling.
Bose has shown this most prominently with the new QuietComfort 30. It’s not an accident that those look the way they do — again, normal earbuds don’t have the space to fit everything that noise cancellation demands.
They’re usually not as bulky as they look.
It’s not like there’s a ton of electronics in there, so most neckbuds I’ve tested have actually come off as lightweight. Plus, since the band does all the heavy lifting, the earpieces are typically on the small side.
Everybody’s doing it.
As noted above. After the success of the Tone, there’s probably money to be made here.
Does any of this make wearing a neckband any less awkward? Probably not. But if you can get over that, it might be worth the style sacrifice.