There are still many things that are protected with a PIN instead of a password. Examples include debit cards, 1Password for iOS and even my iPhone's screen lock. Please consider adding a PIN generator to 1Password.
The next version of 1Password apps, 4th for Mac and Windows will have a strong password generator built into the password fields. You can add custom fields like passwords and set it to generate a 4-digit PIN. There's no need to build a separate generator for this.
We'll look into adding a custom field type of "PIN" and configure the generator to automatically set itself to 4-digit.
Thanks for the idea.