What you're describing is a lack of a functional suspension. While that may be the case with the OP's car, essentially turning the machine into one without a suspension, the end result is what I described, regardless. I don't know what "flexes" means in this context. As you mentioned, I really don't know what I'm talking about and "flexes" figures into that notion. Are you attempting to describe the function of travel? If you are, then asserting that it isn't a necessity on a street car is beyond absurd. It's simply ignorant.
There's that flex again. Is that some off-road term? At least with a car, flex - as applied to automobiles - is the last thing one's after.