I'm going to use a surface mount resistor but I'll have a 2 pin jumper in parallel. The jumper can be off by default, leaving the resistor in circuit. This will make sure there is always a resistor in series with the LED, regardless of the module design.
If the backlight is dim then the backpack resistor can be shorted wit the jumper. OR, even if there is a resistor on the LCD module, the jumper can stay off to have a dimmer backlight using less current. The user just has an additional option.