buck converter inductor lm2576
Inductor ripple current (in an absolute sense) increases with decreasing inductor values.

It is usual to choose an inductor (in a buck supply) for about 30% to 40% ripple current at maximum output current, so as the maximum output current increases so does the absolute amount of inductor ripple current, so the inductance decreases with increasing output currents.

Depending on the architecture, there are other considerations, but setting the peak ripple current is a fundamental step when designing a buck supply.