Historically, exclusivity has played an important role in the game industry. I still remember the day I found out Sony had bought exclusivity to the Tomb Raider series, thus ensuring I'd never see Tomb Raider II on my beloved Sega Saturn. I hated the company for that -- I was still immature enough to harbor hatred for the 'other' console, whatever it happened to be -- but I have to admit now it was a smart business move.
Exclusivity of third party titles is less common these days, as publishers have realized that spreading their titles around makes them more money. Sure, there are a few standout examples, like Gears of War or the original Mass Effect. Both were third party titles, though published by Microsoft Game Studios. Something that's becoming more common though, is exclusive DLC, the most recent example being "The Lost and Damned" for Grand Theft Auto IV.
In theory, the knowledge that exclusive DLC is just over the horizon for one platform might be enough to sway someone's purchasing decision. After all, if you knew there was exclusive content available for your game on only one console, why would you buy said game for any other console? That's the basic question, and it makes sense (basically), but I see a few holes there.
For one, I doubt anyone would actually let the promise of DLC affect their overall console choice. I could be wrong, but it's hard for me to believe that someone eying a PS3 purchase would change his mind because Fallout 3 has DLC on the Xbox. And, of course, it's not like someone who already has a PS3 is going to pick up an Xbox and Grand Theft Auto IV for Johnny Klebitz' sake. Furthermore, how many people even knew about the DLC when they picked up GTA IV way back in April 2008? I know it's hard to believe, but the majority of gamers out there don't obsessively read blogs like this one. Most gamers probably got their first glance of "The Lost and Damned" when commercials started airing on TV.
Granted, I haven't seen the numbers, but it's hard for me to believe that exclusive DLC has a huge effect on console sales, which makes me wonder what's in it for the console manufacturer that pays for exclusivity -- in this case, Microsoft.
I definitely don't see what's in it for publishers. As I said above, the more platforms on which something is available, the more money it can make. It's not like publishers have to spend money on manufacturing more copies and distributing them to retailers. So why make DLC exclusive? I can think of a couple reasons (each as unproven as the last, mind you).
One, a console manufacturer pays a given publisher a lot of money. It would have to be a lot too, like enough to cover how much the content might have made if it wasn't exclusive. Maybe $50 million or so. Otherwise, what's the point? The only other reason I can think of is that making exclusive content is simply more convenient, especially in the case of the Xbox 360. It's generally accepted that it's more difficult to program for the PS3 than Xbox 360, so it might just be a case of developers taking the easy road. Then again, if you've already put time and money into developing a game for both PS3 and 360, why stop at DLC? That makes me think most publishers opt for option one.
But what do I know? The last piece of DLC I bought was the first Halo 3 map pack. Please, feel free to share your thoughts on exclusive DLC in the comments. If there are any developer / publisher types out there, don't be shy about setting me straight either.