Comfort and Convenience
People rarely agree on cabin temperature. Someone who has just walked in wearing a coat warms up quickly, while a passenger sitting still in light clothing cools, so one setting seldom suits both.
Safety and Driver Assistance
Setting the seat and mirrors while stationary turns a fiddly job into a quick one, because adjustments made at a standstill need no timing around junctions or moving traffic.
Multimedia and Connectivity
Taking a call is not the same as listening to music: speech needs a microphone and a clear voice path, so where hands-free calling is used, audio normally pauses until the call ends.