Besides the manufacturing cost on the environment, the biggest down side is the limited range.
I owned a Leaf for 2 years, thanks to Federal and State rebates plus charging it at work most days I actually made money. But the anxiety of the recharge is a big downer and the time to recharge is a killer. I have a friend that use to drive from ATL to Huntsville every month. She had it planned out so she stopped at a dealer in Rome, GA, go a snack while they did a 3phase 240volt recharge in 30minutes. Then stopped again outside Ft Payne, AL and repeated.
Saw an ad for an all electric twin engine general aviation aircraft. Seats 4 I believe and had a range of.... wait for it, 375miles. Taking away 10% for emergency that would get you from ATL to Lake City, FL where you would then wait to "refuel" before you could proceed. You wouldn't be able to make Miami or Key West without an additional stop over.