Actually I think it has less to do with appearance and more to do with efficiency as every mm counts in an electric car drag coefficient.
This table on wikipedia[0] puts the Model S and Prius at the same coefficient: 0.24. The Model 3 is a rounding error better, at 0.23. The Model X is a rounding error worse, at 0.25. Another list with helpful pictures[1] shows that literally every other low-drag mass market vehicle has conventional handles[1].
[0]: https://en.wikipedia.org/wiki/Automobile_drag_coefficient
[1]: https://www.motoringresearch.com/car-news-list/most-aerodyna...
Re: range vs MPG — range anxiety isn't an issue for hybrids, because filling up at a gas station is extremely fast. So having better MPG — which is more a cost metric (and to some extent a badge of feeling good about being eco-friendly) — is less important than having longer range on an EV, because when you exceed an EV's range it's quite a bit more painful than when you exceed a hybrid's range. Technically better MPG means better range assuming tank size is equivalent, but range isn't a number many people care about for hybrids; it usually doesn't appear in marketing, whereas MPG does (and typically without tank size, so range isn't even deducible). For EVs range is one of the headline numbers, whereas MPGe typically doesn't appear in marketing.
For electric it's an amplified effect, because a slightly lower drag coefficient means less energy use per mile, which means you can have a smaller battery, which in turn means lighter, which is again less energy per mile.