Should I be using the "encrypt wallet" feature in Bitcoin Core?
If the computer that holds your wallet.dat file is ever connected to the internet (which it surely must be) then every second that it is turned on it is being probed by thieves attempting to break into it. If any succeed, your wallet.dat file is unprotected and will be copied and used.
If you use email or a web-browser on that same computer then every message you look at, every page you read, creates a very real additional risk that your wallet.dat will be copied and used.
You could buy a cheap letter-punch and stamp your password into a sheet of metal and store it in a very safe place. Don't store important passwords in tiny weak magnetic fields.