How would you play FFXIII online?? 
Turn-based online fights don't sound interesting.
Not online play necessarily, but one of the reasons DQIX sold more than any other DQ ever is the game had new weekly downloadable quests featuring cameo characters and bosses and dungeons, etc... plus it had all kinds of online gimmicks and legitimate multiplayer gameplay. What this all means is that there were FREE reasons to keep your copy to continually get new fun from the game and not sell it back. Thus making it less available at used game stores, have less of a used price drop and that all lead to higher new game sales. It was extremely smart. Something L5 probably learned from Layton sales (which also had weekly free downloadable new puzzles).
Meanwhile the FF team decides to release a game at near $100 that 1.8 million people will beat in a week or two, and has absolutely zero replay value or new material coming. So yeah, when they can trade it back in for at least 1/2 of what they paid (3/4ths+ if they're quick), a hell of a lot of that 1.8 million are selling their games back, the used market floods, the used prices drop, and anyone buying a new copy for $90 next to a mint used copy for $50 is an idiot.
For all the progressive design the FF series has compared to DQ, it's ironic that the DQ series is more progressive on thinking about HOW TO ACTUALLY SELL COPIES
The fact that they didn't even have DLC lined up from the start for XIII is pretty mind-boggling. It's like they thought they were still making a PS2 game in 2005.
