I was actually wondering the same thing a wile back but figure it would turn into a large supply of basically what items are already on AH. This in turn would just have prices fall. If they fall too much, most will stop farming the few things that are farmed. The only way I can see more lower level gear/item on AH is one, we need more of a player base across all worlds, and two, go back in time and kill of the super fat exp from abbysea, not kill the content, just the super fast level gain, or, have the level requirement to get into abbysea 70+. But even if they fixed that aspect now, it would anger a lot of players, both new and old for may reasons.
I believe that SE knows that this game is now dieing, so there just having fun with it, teasing us with other things, and overall just handing us things till we all quit. Even today, the only reason I did anything is because my wife was adventuring along with me. I belong to.... lol I got off subject...
Yeah, um... too many of same items will have people undercutting massively, everything will cost 1 gil, everyone will have everything except the ones that don't. >:P