That's because the look of a Lamborghini is one of it's core signature elements. They could design a very nice looking car, but if it doesn't look like a Lamborghini, then a lot of their client base would be disappointed.

You'll notice this pattern with many of the really high end cars. Some signature elements are always present and evolve only very slowly over time. You could call it the master stroke, it's what makes a particular brand distinct from others. This is deliberate and I for one like that.

A complete newcomer can design whatever they want right away.