Companies are in the business of making money, and the video game industry is no different. The current-gen systems allow developers to expand their cash by offering additional content for an already released game, something that could not be done back in the Sega Genesis days. These video game big-wigs will try anything to make a buck off consumers, and you can't blame them since that is the nature of any business. There are a variety of ways this can be done, and in the end only you can decide whether you are being exploited or not.
The first type of DLC I will refer to as "cosmetic content." This is the stuff like character skins and avatar clothing that do not add any game play value to any said game, but attract the consumer with a purely visual look. I will admit that I have given in to this cheesy cosmetic content, and I spent somewhere between $3-5 (I forget exactly how much) to snag a New York Rangers jersey and hat for my 360 avatar last year. It's not like this stuff will gave me +10 to slap shot accuracy while playing NHL '11, but I made the impulse purchase just because I wanted to show off my Rangers pride. But it's each to their own...I personally won't spend $1 to throw a Mickey Mouse skin on Sackboy but I'm sure there are plenty of people who will drop cash to get classic outfits for their favorite Street Fighter and Mortal Kombat characters.
The next kind of DLC is what I generally refer to simply as DLC. This is the good stuff that actually adds gameplay content to a game. This isn't just about new characters (though I will count entirely new characters in this category...as long as they are not just skins), but added levels, maps, additional quests or a whole-new gameplay mode. One of my favorite DLC add-ons of all time is Oblivion's Shivering Isle Expansion. Sure it cost $30 at the time of release (you can get it much cheaper in the GOTY) but it is worth every penny. It doesn't feel like you're just adding a new dungeon or some new enemy types to the game...it feels like a totally new game! If every company put that kind of dedication into their DLC you could guarantee getting a huge bang for your buck. Then again, this came from the same company that created horse armor for purchase. Once again it comes down to whether the content being offered is worth your hard-earned cash. Personally, I find DLC that extends the replay value of a game with new modes or levels the best you can get.
Then you have the newest type of DLC, and it's the most evil concept ever created. The very mention of the term "online pass" should cause any gamer to feel an uncontrollable urge to hurl, and with good cause. Gamers are already paying for the privledge to play online by paying their internet bill, and this goes double for 360 owners who not only pay their bill but also have to shill out for a Gold account. Now let's say you rent Mass Effect 3 (times are hard and you can't afford it) and can't wait to play with all your interwebs buddies. You pop the game in, and go to jump online, but are shocked to discover you cannot unless you provide the code for an online pass that is present in new copies of the game or you have to spend $10 for an online pass. It's crazy! You have your internet bill, then your Gold account, and NOW they want you to spend even more just so you can spend a few hours taking on missions with your buddies. It's absurd!!!
This type of DLC is the biggest exploit of all. It potentially charges gamers a third time just to access online content if they don't happen to purchase a brand new version of the game. I understand that game companies need money to support servers and whatnot, but this is not the right way to go. Now I don't have any sales data or stats, but I would love to see if companies are actually making cash off of this. In my mind, this actually causes a loss in sales. Take my personal case. I rented Mass Effect 3 from Gamefly but was unable to even try out the co-op mode (they didn't even offer a trial period, like several companies do.) If I had the ability to try out the online modes, chances are I would have loved it. If that was the case I would have ended up purchasing the game. But without being able to try it before I buy it, they simply lost a sale. I'm sure there are plenty of people out there who have had similar experiences with online passes.
So let's bring this all together, since I'm kind of all over the place. DLC is not an exploit unless you actually want to pay for it. I may think that cosmetic content and background themes are a waste of cash, but if you are willing to pay out for a different colored attire for your favorite character, then more power to you. I definitely don't find DLC in the form of additional content (levels and such) a bad thing, but you may find it as the work of the devil, and you are entitled to your opinion. I believe that online passes are a horrible concept and they need to be stopped at all costs. The gaming companies will only provide services if there is a demand for it. I encourage everyone to boycott online passes...by not paying for them companies will see there is little value in them and might halt this unholy abomination.
As the consumer, the power is yours. The only DLC that will come out is DLC that consumers are willing to buy.