Yes, their battery tech is improving, and they make pretty damn good cars, but most of all Tesla is getting people excited for electric cars.
Before they came around, electric cars were shitty ecoboxes that were worse in just about every way to an ICE car. They were ugly, had no range, were missing features, expensive, slow charging, etc... There were exceptions, but for the most part this was what the average person believed.
And while you could argue that much of this is still true with Teslas when compared to other luxury brands at the same price point, Tesla has gotten people interested. They've gotten people excited for electric cars. They've made people want them even though they might be worse on paper.
And that's a big deal. They are not only making a great product, but they are pushing their competitors to step up their game and really focus on their electric offerings.