ahahaha the only difference is soldered RAM and none of the cMBPs will drive more than 16GB RAM regardless, so what's the point? I would understand the complaints when compared to, let's say, ThinkPad W540 which has 4 SO-DIMM slots and therefore supports 32GB, but the current MBP layout won't accommodate so many memory modules
Apple charges $200 for 16GB in a 13" rMBP while you can get the same amount of memory for around $100. You also have the original 4GB modules which you can drop into an iMac if you have one. Also, you can put a 512GB SSD pretty easily on a cMBP, while you'll have to wait until PCIe blades become available for rMBPs.
I think there is room for discussion when buying 13" Macbooks. On the 15" side, the decision is pretty easy though. Just buy the base 15", maybe order a bigger SSD and you're fine.