I think I see where part of our disagreement lies. You say, "...the person who overcame X disability/background in order to become the best Y in the land...", but in my mind, if there's no penalty to being blind, it isn't really a disability and you haven't really overcome anything. I guess the question is, did your character overcome it before you as a player ever got there, in which case it's just backstory, or did you actually overcome it during the course of the game (by learning skills/feats or acquiring items/rituals that counteracted the penalty).

If Sighted Joe fights Blind John, the smart money should always be on Joe. If John has the training, etc. to overcome his blindness it should be represented by something on his character sheet. This is why you generally get points for taking a disadvantage like blindness.

As for your example of the elf and dragonborn monks, yes, along strictly monkish lines, the elf will be more effective. However, if they jump off a cliff while running from the advancing army and the dragonborn spreads his leathery wings, odds are he'll be more effective. Also, when he kicks you in the face, he can follow it up by breathing lightning on you. Just depends on what you want to do.

Anyway, this is D&D. In another month and a half I'm sure there'll be a book with Dragonelfborns in it.