The legend of Korra

[Brother Oni]

So yeah. The sport is just dodgeball then. What a waste of the bending concept.

Your not even allowed to target a single person with multiple bending types at the same time then.

I have to question whether you actually paid attention to the pro-bending matches, or were too busy getting righteously indignant because the creators didn't do things the way you wanted?

A single attack can only be composed of a single element type. There's nothing illegal about two different players attacking the same player simultaneously - hiding an earth attack behind a water attack is perfectly legitimate and was seen in an earlier match.

As for a 'waste of a bending concept', why don't you go back and watch the original series since pro-bending apparently irks you so much?

I'm sure the intention was to show how bending itself has become common to the point of sports entertainment, and give the bad guys a target for later on, but really... I always faded out when it came to the matches because I just didn't care that much.

I understood pro-bending to have two reasons; the first was as you stated (bending becoming so common to the point of it being a sport), and the second was a way to have Korra being able to practice in a competive environment.
Aang and the others had an actual war with enemy soldiers to fight and 'practice' with - Korra doesn't and since going round like a vigilante didn't work too well (as seen in the second episode), she needs something almost as high stakes but socially acceptable in a society not in open war.