When well-crafted, it's a great thing to have such irreversible decision points. The fundamental flaw with the pie is it wasn't well-crafted (both in-game and in the larger ecosystem of adventure games at the time; players were encouraged to try everything when stuck, so they might eat the pie even if it wasn't an obvious solution to the current problem. "Can't climb this cliff. Maybe eating the pie will give me wings? That magic stick gives you wings in that other game...").