It does feel like this is such an untapped market. Think commuters, credit cart tourers, tourism around a spread out city. Something that is safer than a motorcycle and faster than a bike.
And this is borne out in the statistics -- there's no reason to believe motorcycle riders are any better or worse than cyclists at bike handling / driving skills, but the motorcyclists certainly die more on average. I suppose if you're an amazing motorcyclists but a shit bicyclist, stick to motorbikes, but that seems pretty far-fetched.
(Safety gear like armored jackets, pants, gloves, and boots -- available to motorcyclists but impractical for cyclists -- certainly helps at the margin. Nevertheless, the stats are worse for motorcycles. I'm not saying don't ride motorcycles -- I have in the past and will again. More speed just doesn't make you safer.)