So, we want to model disabilities that we expect won't really be an issue, because the heroes overcome them anyway?
I twisted my ankle, so I have a limp - but, when it really counts, I push past that and can get the job done. If someone came up to me and tried to kill me, it'd be a bit easier than if I were whole, but otherwise it doesn't actually stop me when the chips are down...
There's a desire to put in modifiers, sure. But, if, when all is said and done, we expect (and thus design the system so that) the hero *will* overcome those modifiers, why are we putting them in at all?
I speak for the system as it is written and presented as well. Once again, 081312_How to Play.pdf, page 13, "Hit Points" paragraphs under the "Damage and Dying" header, especially the second paragraphs.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.