On the flip side:
(1) Running low ATV's gives you faster control surface speed ie you get to your 15mm of travel faster (not so important?)
(2) You get better surface deflection vs servo rotation linearity (which would probably get cancelled out with more expo)
(3) Linearity errors resulting from small differences in linkage geometries are minimised.

Using the full range of servo travel ensures you enjoy the full mechanical power and resolution of your hardware no doubt, but giving up a little bit of torque and resolution isn't all negative...