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.