We want to believe that we are smart and intelligent people with an open mind and in fair disposition to settle our differences through talking. Unfortunately, that is not true. Our brains are way more wired to 'win' than to 'learn' or 'come to an agreement'. It does not matter the subject, if we already have an opinion, the chances are we will defend it at all costs, no matter how many facts on contrary are throw at us. We don't want to be in the wrong side, so instead of admitting a mistake there is a greater chance of us defending our point of view with all our might. Because we don't want to admit to being wrong.
In theory, the Internet would be a great place to have a discussion, as it is very open and there is few to no retaliation against us for expressing an opinion, no matter how polemic and divisive it can be. But because of our nature, this need to 'win' a discussion, those discussions usually ended up fruitless.
The first mistake everyone do is choosing where to have this discussion. Site forums looks like a good place to start. What a better place to discuss if DLC is good or bad than a gaming site? Except that we tend to go to sites (and hang out with people) with similar opinions as we have. So, if you are against DLC, you will likely go to a site whose public have similar opinions as yours. And there is no discussion if everyone have the same opinion. But because we want to be a part of the group, we usually will seek for people similar to us to be part of the group.
And because of that, if you go to a site where people are OK with DLC and try to show your arguments as why you think DLC is bad, you will probably be confronted with an unwilling group. The group will unite against this stranger who dare to have a different opinion. Many times, even when they agree with you, if you confronted on people of the group, they will go in defense of their fellow member, their friend. Everyone do it one time or another, defending a friend for the sake of friendship, not because he is 'right'.
Another problem is that we usually start this kind of discussions with the wrong people. See, people in those forums are hardly specialists in the matter in discussion. If you go to a game site, the chances are you will have this discussion with other gamers, people who only experience with games are playing with them and going to the Internet. The chance of talking with someone who actually work with making games and have the knowledge of all the process of making and selling them is very small, at best. And they also have the tendency of not wanting to discuss problems with people who have only a superficial (an many times wrong) about a subject.
See, a medic will not start to talk with a patient the merits of a treatment against another and just because the patient got sick once does not make him qualified to talk about medical procedures. And the Internet have way more people who have no idea what they are talking about (or have the wrong idea) than people with the needed experience and knowledge to make an informed opinion about something.
I know I am pretty guilt of all the sins above. And probably everyone on the world have done this at least once. But my time on the Internet showed me that if I stop trying to 'win' and start trying to 'learn' I may get something of it. Everyone have the right for opinion and to state it. But before defending the opinion, it is better to listen first, check the facts, seek for the truth and make a well based opinion.
Being wrong is not a problem. Insisting in being wrong is.