Well of course the starter has been key in making the car more convenient, but this piece is of course about the drivetrain, not the individual component.
And you've touched on what the battery electric car of the future needs, a damn good battery. That has always been the biggest challenge to a legitimate battery electric car. It's why they died off in the 1st place too.
Thankfully, battery technology always seems to advance exponentially, just take a look at how far we've come with cell phones in the last 5+ years.