Subject: Why doesn't increasing the surface area of a solid shift equilib position?

I am an IB Chem teacher and can't seem to find a logical answer to this 
question. Equilibrium constant expressions do not include solids because their 
concentration doesn't change. However, increasing the surface area of a solid 
reactant increases the rate of the forward reaction (more collisions). For a 
system at equilibrium that involves a solid reactant, why does the equilibrium 
position not shift to the right if more solid reactant is added, since 
effectively the surface area of the solid reactant is increased? Collision 
Theory and Le Chatelier suggest that it should, but it can't since it is not 
involved in the expression for K.

Re: Why doesn't increasing the surface area of a solid shift equilib position?