I don't know why, but can venture a guess. This piano is an edited version of the Natural S6 - since this is a "Rock" treatment, perhaps they felt the subtleties of Damper Resonance would be as meaningless in its use case; same as several velocity swaps in the soft to medium range would be a subtlety mostly lost in heavy "rock" style play. Being a "Rock" piano it seems to be setup to punch and cut through a band with distortion guitars, and loud drums.

The mystery is why would you expect Damper Resonance 🙂

Good news is, they left the Damper Resonance assigned, so those who find its lack of use mysterious, can simply change that Dry/Wet Balance to your liking... store your version to the User Bank.