I agree with you. The 13" Retina seems to exist just to make the 15" Retina look like a better buy! It is a shame because a lot of folks want a highly portable machine these days. I do suspect that thermal constraints resulted in no dedicated graphics option. But the Core i5 and HD 4000 graphics just don't impress like the standard Core i7 quad core and GT650M graphics in the 15" model. *sigh*
Apple's SSD pricing has always been steep, that doesn't surprise me.
-------------------- Lisa Gade Editor in Chief, MobileTechReview