Perhaps the better question is why "restore" (to whatever period) at all? What's to be learned about how our ancestors... lived, or thought...?" Some ignorant clods either allowed this... to fall down or pushed it over and now no one wants to pay to put it back up"?
Perhaps you would also like to apply that philosophy to Coventry Cathedral, Dresden, the Globe Theatre, the Sutton Hoo helmet, Pompeii, the Mayan pyramids... perhaps even the Twin Towers?