Address and Public key
There are several aspects to not sending to a public key directly. Here are a few I can name


RipeMD160 shortens the address from 256 bits to 160 bits
A checksum is introduced to the address
An address doesn't expose the pubkey, so if the ECDSA gets compromised, funds are still safe ["quantum PC attack resistant"]
Pay to script hash is possible with the same address format; in later iterations with e.g. taproot this can greatly enhance privacy and functionality at little or no extra on-chain cost