Because the US legislature stopped making laws

They haven't stopped making laws. We are inundated with new laws every legislation cycle (the current cycle being more an exception than a rule). But the enforcement of these laws is up to the various USA offices. And the judicial bench has been stacked with ultra-conservative judges more interested in Christian morality than civil rights or social equity.

Consequently, what laws we do get are often twisted against their stated purpose by subsequent administrations.