In my experience, most people don't have their load or their zero dialed in enough for the difference between 1/8 and 1/4 moa clicks to matter much when it comes to hitting what they are aiming at. Throw in wind, mirage, other changing environmental conditions such as temperature, barometric pressure, etc. and your 'zero' is going to vary more than the difference between 1/8 clicks and 1/4 clicks... There are times its nice to be able to correct say, 3/8 moa instead of either 1/4 or 1/2; it's just about as easy to correct a 1/4 and hold off a fuzz...
YMMV,
Monte