Well it's easy to create nice looking 3D models (like the renders in the article). But designing a real car is something completely different. Aerodynamics, weight, space, it's all what costs a lot of R&D.

I think this is why Tesla was working with Lotus on the Roadster. It's very hard to design a car from scratch.

But lets hope they succeed. It might be a good boost for the country.

I guess the form of the car is very much a trade off of competing interests - cost to build, ease of maintenance, available space, etc. Since you asked specifically about lower end cars, I'd say it's just that supercars have their preferences set very differently than low end cars. Nobody cares if this car doesn't have good boot space, or is expensive to repair.

"which is expected to cost an Aventador-like $400,000"

I suppose is low-end compared to a Pagani Huayra or other obsessively engineered hypercars:

https://www.youtube.com/watch?v=ga7_w4Ib2MM