FCOM 3.04.10 is the chapter of Operating Speeds Definition.
Read the entire definition:
VAPP
Final approach speed
Displayed on MCDU APPR page
Calculated by the FMGCs
Represents: Vapp = Vls + wind correction
The Wind correction is limited to a minimum of 5 knots and a maximum of 15 knots.
The flight crew may modify Vapp through the MCDU.
– During autoland or when A/THR is on or in case of ice accretion or gusty
crosswind greater than 20 knots, VAPP must not be lower than VLS + 5
knots.
To me, this means that the FMGC will always add 5kts minimum to the Vls for the Vapp calculation. So it will always cover the 5kts increment for autoland, auto-thrust and gusty crosswind, since it doesn't know if you will fly with auto-thrust or not or if you have gusty crosswind.
If you want to calculate the Vapp yourself, you're in the wrong chapter of the FCOM. Calculation is explained in the QRH.
FCOM 3.04.10 is only the definition of Vapp, not the calculation.
So in case of:
-No wind
-Approach without auto-thrust
-No ice
the FMCG will give you a Vapp = Vls + 5kts.
You can however change the Vapp in the MCDU to a manually calculated Vapp = Vls according QRH.
The only reason for landing with Vls I can think of, would be a very short runway. (Close to required landing distance)
Or according overweight landing checklist.
Not sure if I'm correct, just my opinion about it.