You should create a new receiving address every time you are requesting a new payment to your wallet.
Is that for privacy?
It is a recommended best practice.
It increases security slightly.
It increases your privacy.
It increases the privacy of everyone that you transact with.
It improves the fungibility of bitcoin over all.
It allows you to easily identify who paid you for what and when. If you are expecting a 1 BTC payment from me, and you are expecting a 1 BTC payment from someone else, how do you know which of us paid you if you give us both the same address for our payments?
It discourages people from forming silly (and incorrect) ideas about how bitcoin works.
It was recommended by Satoshi Nakamoto in the original white paper:
https://bitcoin.org/bitcoin.pdfa new key pair should be used for each transaction