They need to incorporate a large, heavy battery that needs to sit at the bottom of the vehicle for stability. That means a large footprint to keep a low roofline, or a high roofline for a smaller footprint. All EVs must work battery and range into their aesthetics, and it's a design imposition. The Tesla Roadster looked good, but it was a based on a Lotus ICE and traded interior space for aesthetics, as well as limited range: too impractical for most.
The Prius looks dull because it's tuned for ultimate efficiency while also paying a small roofline/footprint penalty for its battery in aesthetics. It would be interesting to see what a max efficiency ICE Prius would be like. I bet it could do high 30's mpg, maybe even 40, would look better, and be substantially cheaper.