Simply negate any bonuses from gildings that is has on it.
Hair actually looks nice, and the closest thing to a No hat Hat that we have are laurel wreaths, and we can't even gild those :<
W3 to W6 - Blockland. Special mentions: New Avalon, Tarn of Hotdog, Red October. W7 - Elvenia, til we all got lazy. W8 - Cult of R'lyeh, til the deeps called us back. W9 - Tartarus, til death/wizards came for the land itself. W10 - ???, ruined and forgotten.
I agree that there should be a "No-hat" cosmetic option.
"The psychological trials of dwellers in the last times will be equal to the physical trials of the martyrs. In order to face these trials we must be living in a different world."