I'm not sure its the futuristic design people don't like, but rather the substance of the car itself. All too often car manufacturer's put form over function and produce cars that are radical looking but don't drive particularly well.
If you remember when the Ford Taurus first came out, mid-80s or so, it was one an extremely futuristic design (as compared to the other boxy cars in its segment), but it gained popularity because it was also a fine car, one of the best in its class.
In addition, the form question can be a highly subjective one. Manufacturers are hesistant to take chances, especially if the end result turns out to be a detriment on function. Again, the Ford Taurus is a good example, with the second generation being too radical for public taste.
I personally like the design of the Audi A6, however many of my friends feel that it looks like a bar of soap. They prefer the edgy look of the new cadillacs....
As you can see, manufacturers face this type of problem with each model they design.