Question

1. what are software updates?

fixes for known problems in the software
new software programs
new hardware
new icons

1. why do computers have and use power states?

to keep computers from wearing out too quickly
to save battery life and to save energy
to dim the monitor display; a dim monitor is better for users eyes
to give users something to do trying to wake up the computer

Explanation:

Software updates are designed to fix known problems in the software. This helps improve its functionality, security, and performance. New software programs are separate entities from updates. New hardware is related to physical components, not software. New icons are just a visual aspect and not the main purpose of updates.
For power states, computers use them mainly to save battery life (for laptops) and save energy (for all computers). Keeping computers from wearing out too quickly is not the main reason. Dimming the monitor for eye - health is a side - effect in some power - saving modes but not the core purpose. Giving users something to do when waking up the computer is not a valid reason.

Answer:

1. fixes for known problems in the software
2. to save battery life and to save energy