In the mad rush your lawn is moved , weeded, fertilized and irrigated , the need for aerating is often overlooked.
But as sod ages , the soil underneath can become so compacted , is lthere ittle or no pore space  ( small pockets of air held in the soil ), making it difficult for grass roots to absorb water and nutrients.
Before long the lawn will deteriorate ,becoming more susceptible to weeds and attack by insects and diseases.
Aeration / Detaching
Aeration involves perforating the soil small holes to allow air ,water and nutrients to penetrate the grass roots.

This helps the roots grow deeply and produce a stronger, more vigorous lawn.
The main reason for aerating is to alleviate soil compaction.
Over time, little bits and pieces of grass die and gather just above the soil. This is called thatch. A little bit of thatch can be beneficial. Its an organic material that is broken down by microbes in the soil. But sometimes , thatch builds up too fast for naturel processes to break it down.
Its forms a barrier, keeping moisture and air from going where your grass needs it.
A half-inch or more of thatch can weaken your lawn.
You have 2 ways to remove it:
~
Detaching 
~
Aerating

Witch one you chose its all depending on the conditiones of your lawn.

When your Thatch is more then an  1/2 inch we can considering doing it but without the dilemma of  ruing your lawn with to deep detaching.
Aerating is considered a better way to maintain your lawn since it puts less stress on it.