Intake temp (at the air filter) is important on any engine, turbo or N/A.
Intercoolers do cool the air, but only by a certain percentage and only once the act of compressing it has already heated it massively.....The intercooler does't have time to cool it back down to anywhere near the ambient temp, so the colder the intake air the better.
If for example the air temp at the filter can be reduced to 20C instead of 30C, then that 10C difference carries all the way though the system, so the air entering the cylinders will be roughly 10C cooler as well.
