[E90Fleet]

Not only are the air curtain and breather intakes not simply for aesthetics but for many engine models the other front intakes are essentials.

Some engine models need little cooling but others need a lot, like:
1) Main engine radiator
2) Secondary engine radiator
3) Intercooler fluid radiator
4) Oil cooler
5) Transmission oil cooler
6) Steering fluid cooler
ect ect

Then the sportier models need extra brake cooling and hot country versions need even more cooling.

So you may find 1 car that uses only a few of the intakes, but another with a different engine and gearbox that requires all the intakes.