Those spring rates are setup for the jdm style of suspension. The japanese tend to like large spring rates in the front and lower in the back. It is also very popular to use large rear bars in the rear which would help the low spring rate.

This also helps in the weight load transfer while braking at high speeds on road courses since tegs/civs are front heavy.

We, the US, tend to like stiffer rear rates because it promotes oversteer which would counteract understeer. This is very useful for low speed corners such as those found on auto x courses.