Cormoran: Yeah they don't have same sex marriage, but I'm sure they don't have a LOT of what the Sims has to offer out of the box.
Potzato: I don't think many Europeans really feel offended/relieved by such an omission.
Sorry that I picked you two, I could have picked a couple others for the point I am going to make, and chose randomly ;)
I see many comments calling this an "omission" or a "decision to include or not include". Actually things are a bit different, and that may be part of the problem, at least for some of those who feel indeed discriminated by such a decision. Please allow me to explain.
When you program a game, and include marriage, then - by default - gay marriages are always in. They don't need to be specifically "included". If you just program a feature that allows characters to marry, then there is nothing which would prevent same-sex marriages.
In order to _only_ have opposite-sex marriages, you have to specifically
exclude the same-sex ones. You have to spend time and effort to sit down and write code that specifically checks the gender of the involved characters, and specifically says "No" to marriages of the same sex. It's a bit different from "not programming a wheelchair" or similar comparisons that have been made. The only way to not have gay marriages in a game that allows opposite-sex marriages, is to make a conscious decision to write code to exclude them.
For people belonging to a minority which is often the subject of discrimination, this can hurt immensely. As an example - imagine that someone wrote a business simulation that allowed only white characters to head huge corporations and become billionaires. Blacks can play, but can't rise high enough to earn that much money, only whites can. Given that about 5-10% of people are homosexual, whereas less than 1% of billionaires are black, it's even more "realistic" to exclude blacks from becoming billionaires, than it is to exclude homosexuality from a life simulation. Would that be okay? Moreover, would it be okay if the respective company said that they simply "didn't want to make a social commentary in one way or another"? Also, would it be okay if people defended that move with arguments like "They don't have to give blacks the opportunity to become so rich in their game, black people don't get so rich in real life either" (which is actually more correct than saying that gay people can't marry in real life, if you look at the numbers)?
The only difference, really, is that it's currently more socially accepted to discriminate against sexual orientation than it is to discriminate against skin color. And that's the problem: The failure to see that both are discrimination. And the people who are discriminated against have all the right there is to raise their voices. Yes, there may be bigger battles for them to fight than this particular one against Nintendo, but I would never criticize anyone for standing up against discrimination, no matter if the particular case is a "small" issue or not.