Q: iOS: Updating your carrier settings_ what do carrier settings do?

These are settings an updates from your wireless carrier.

You need to do these.

Connectivity to the carriers network.

Why the hesitation to update? or better question, why do you care?

If you want the best connectivity, do the update.  If you do not care if there are connectivity issues, don't do the update.  But at the same time, do not complain when you have connectivity issues.