Don't know about you, but I personally don't ride a motorcycle simply because there are so many larger vehicles out there that would vaporize me without losing momentum. Same goes for some sort of plug-in motorcycle - there is simply NO WAY that can be as safe as a vehicle if, as you said, we'd still need larger vehicles around to go on trips or to carry around a group of people, as in a family. So basically you'd have big cars and little bikes... so in any accident one is coming out with a dent, the other is having its driver's limbs located.