It does seem like Tesla Motors is the only company that believes an electric car should look like a "normal full-size car,"
They don't have any other models to fall back on, so they are forced to "conservatively" design a car that is visually "acceptable" to just about everyone.
The big automakers have much more freedom to experiment with different designs>
The big automakers aren't "experimenting". Making an electric power-plant that fits their performance and mileage needs to compete is difficult so they're using the easiest target to get there -- a chassis that's the lightest and chintziest possible while still meeting safety requirements.
Look at the body style of that car, and compare to a Toyota Prius -- not a huge difference in vehicle body style.
Look at that car and compare to econoboxes of old (Ford Feista) -- still a hatchback box. Just has before.
Where's the "experimenting" in copying old designs for electric and high-efficiency vehicles?