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Somehow, I don't think Aang could have taken away bending from the Fire Lord unless he had met up with that turtle-lion. And, it was probably only a one time thing; he can't do it again.

Also, giving normal people bending would destroy the balance of the Avatar world. They were born normal people because they had to be normal. Benders were born benders because they had to be benders. (I know, redundant, but it still makes a point.) If everyone in the Gaang had been benders, things would be different, and probably easier. Being a non-bender opens you up to more potential elsewhere (Sokka and his sword).

Energybending

Aang is also able to use an ancient form of bending called Energybending, which he used to strip Ozai of his bending, leaving him permanently drained and in a state of weakness. According to Lion Turtle, before the Avatar existed, people didn't bend the elements, but the energy within themselves. However, in order to bend another's energy, the benders own spirit must be unbendable, or they can be corrupted and destroyed. It has been confirmed that Aang is not the first Avatar to learn Energybending. There have been others. However, there are few who have learned this bending and even fewer who have used it due to its dangers.