It's not possible to paint the switch mounting plate without desoldering and removing all the switches. But you CAN reinstall those same switches after the plate is painted.
Whether it is worth it or not is up to you. It will rarely be seen, because it is hidden by the keycaps. Whether the Poker is backlit or not makes little difference. Now, if it were me, I would only desolder the switches to replace the plate with a custom one, like the ones LeandreN was selling recently.
And finally, welcome to Geekhack!