I believe unicycles are a better fit for urban mobility (I am talking about proper, mainline EUCs, not the Onewheel bastardization of the technology).

You can easily use them together with public transit systems, while e-bikes are quite unwieldy. The have better maneuverability and responsiveness. They do not require any parking spots and can be easily taken to an office.

They are a bit more dangerous than e-bikes, but with proper protective gear and improvements in the technology (chances of mechanical or electrical troubles are very low, if you don't intentionally push hardware to the limit) the difference is quite small. Also, they are somewhat harder to learn to ride, which hurts their popularity.