A couple weeks ago, users were celebrating an awesome win for getting Blizzard to finally implement public chat in the game. (Though many believe Bashiok's claim that it was just a mistake.) Whatever the case may be, it's considered a win.
"Blizzard listened to us! We get public chat! Now I can trade items with other players and I don't have to worry about using the RMAH!"
Is this really the case though? What if it's just simple Public Chat, but not intended for Trade Chat? What if trading between players will actually be discouraged or difficult?
If I were Blizzard and I wanted to encourage as much use of the RMAH as possible, I would restrict loot linking, eliminate ways to communicate effectively for trade-specific purposes, or make trading as challenging as possible (for example, poor trading security.) Using a "Trade Chat" system outside of the game (ie, in the lobby room), without the ability to link items, is a great way to do it. Or, one could also make it so that players can't create public games with customized titles (like how trading could be done in D2).
You only need one of these options. If you have secure trading methods, then eliminate trade related communication methods. If you have proper Trade Chat, make secure trading more difficult. You don't need to do all of them otherwise their intentions become too elaborate or obvious. When players question why, Blizzard can confidently tell them that they DO have methods in place to allow trading.
The average player will always travel the soft path. If there are two services available, but one has accessibility or functional issues, they'll go with the easier one. If character-to-character trading is available (and secure), but public chat is limited so that it doesn't support loot linking or gear sharing, it's not a very good service. If public chat has loot linking, but item trading is insecure, it's not a very good service. In both cases it's "bad service" planned in advanced to encourage customers to use a better service.
So, which is the better service.. player-to-player trading or the Auction House?
We really don't know anything about the future Trade Chat features, though. It could go either way. Bashiok had promised details in the near future, so it remains to be seen what Blizzard has in mind. If the chat or trading features are still limited by retail, then we have our answer. If not, then Blizzard will act accordingly to their customer's needs.
Nothing is set in stone at this point. In it's current disappointing state, it requires more forum outrage and complaining, and hopefully Blizzard will eventually implement chat the way players want. If they, however, are looking for every little way to squeeze as much use out of the RMAH as possible, then don't expect loot linking or any other kind of trading mechanisms (like customized public games) in the initial retail version. Besides, if Blizzard won't implement these changes, someone else will always find a way, like that alternative "trade chat" website.
Just as an added note, too, Bashiok happened to make a comment about the Chat system recently as well. Basically, it's not to expect any changes before release. So, this is something I might re-examine 6 months after release (as well how or if players can even engage in some form of public trading without an external website service). But atleast you can understand some of the motivations behind keeping the chat system the way it is. And judging by the SC2 Chat System, I'm not really expecting Blizzard to make any significant changes.
I hope that D3XCHANGE.COM webpage was still being worked on though. :)
* UPDATE (03/01/2012):
Just an interesting note. Recent data mining of Diablo 3 revealed that Blizzard did, in fact, create a UI within D3 for users who wanted to create a custom named public game. So this feature was once in the game, but has been removed. Guess we'll see if Blizzard puts it back in for retail.