i think it would be useful to trade qi. Instead of just trading tc and items :P

Not supported, I think you should earn your Qi and not buy/trade it.
It's supposed to somewhat show an estimate of your skill level in my opinion.

You can trade qi its like 500,000,000 tc for 1 qi (might be 500,000 not shure)

Qi is meant to be earned, or bought from the torishop. This would open a whole world of problems in toribash. You would have people qi farming to get tc, people would make a million alts to transfer the qi to one account, and a whole other mess of things. Not supported.

Since you already can trade it for 500k per qi. And that price is there for a reason. Not supported.

Also would become farm farm farm.