There are various frameworks around which enlarge the category of rings to include more exotic objects such as the 'field with one element,' $\mathbb{F}_1$.  While these frameworks differ in their details, there are certain things this should be true of any object that deserves to be called $\mathbb{F}_1$.  For example, The algebraic K-theory of $\mathbb{F}_1$ should be sphere spectrum, and the theory of toric varieties should be defined over $\mathbb{F}_1$.

Is there a moral reason why the moduli space of curves should (or should not) be defined over Spec $\mathbb{F}_1$?

EDIT:  For anyone who would like to be more concrete, I'm happy to  take the Toen-Vaquie definition of schemes over $\mathbb{F}_1$.  (see [arXiv:math/0509684][1]). 


  [1]: http://arxiv.org/pdf/math/0509684v4