why are some items tradeable only through AH?
 

Hi, I was wondering if there's a logical reason for some items to be tradeable only through AH.

Don't think anyone will sell a boss weapon (for example) for gold, so a boss weap in AH means it is being traded because It can not be traded directly, and it has its risks.
Dont understand what the intention is, the only thing it adds is the risk of someone losing an item that is trying to trade.

probably to give some attention to the AH

Same reason why dragon hearts/souls are not able to be traded.

To make us sad