At this point, I'm sorry I used the halfling barbarian as an example, because everyone seems to be focused on that specific idea instead of the bigger picture.
In some/most/all systems, there are character concepts that do not work as well mechanically as other character concepts. We can all agree on that, right? So is the argument (a) that that's a good thing because those character concepts are bad or (b) that that's fine because the gap isn't that big? It seems like people are trying to have it both ways.
I feel I've already been pretty clear about my answer to (a). Namely, a system should be subordinate to its players, and not the other way around. If you're arguing (b), then if you'll pardon me, I'm exiting stage left before someone drags out the spreadsheets and the personal anecdotes.
The more balanced a system is, the less difference there is -- the less difference there can be -- between a roleplayer and a powergamer. I consider this a good thing. When I sit down to a game, I don't want to be forced to choose between making a character that's fun and interesting, or making a character that can pull its weight and not force the GM to throw wimpy encounters at the group. I don't feel that having to make that choice is either fun or necessary. To those that feel differently, I respectfully I have nothing further to say.