Why not change the terminology of "Rage" to "Fury"?
Rage: calls to mind the idea of "Losing Control" which is specifically implied in their alignment restriction. The word "Fury" does not necessarily have the "loss of control" interpretation intermingled in it. You could be a Holy Warrior that is "furious" at any "evil target", you could be a Lawful person that is focused purely on a successful strike to the detriment of your own defense.
The Bbn powerset as is offers more than enough options to accommodate any alignment (see Rolling Dodge, Guarded Stance, Moment of Clarity, Renewed Vigor, Surprise Accuracy)
Rage: 1 a: violent and uncontrolled anger b: a fit of violent wrath c archaic : insanity
Fury: 3: extreme fierceness or violence 4: a state of inspired exaltation : frenzy
The use of the word "Rage" calls to mind the generally chaotic, uncontrolled anger, which most barbarians are, but look at it this way: If you can remove the alignment restriction from bards, and the debate is going for monks (see the thread "Retiring Alignment Requirements" especially Tektorman's post in the middle of the page) why not for barbarians as well?
Why not change the terminology of "Rage" to "Fury"?
Then rage could be an example of furies. There could be more than one available at character creation, with different statistical advantages and flaws.
'findel
Because it's completely unnecessary to do so.