I think what you are seeing is not so much a blanket approval of oppression of women in Muslim countries, as a lack of agreement about what is going on and what we should think about it. There is a great deal of agreement about the fact that slavery and the holocaust being terrible events, and a general recognition that the racist ideologies held by the perpetrators of these crimes were a motivating factor. Unless you hold one of these racist ideologies, neither slavery in America, nor the holocaust in Europe are likely to be considered permissible in any ideology you hold. But different ideologies have different things to say about the life of women in Muslim countries.

There is a popular relativism held by many, which is motivated more by optimism than by any consistent, rigorous thinking. It says something like the following: different cultures face different challenges. Each has invented a system of norms for dealing with the challenges they face. Our own culture has arisen in the same way. There is no sense in which we can say that our culture is better than any other. To do so would be to just judge them by our own standards. Rather, we should look at what reasons motivate each culture and see why each culture functions the way they do and what people living in that culture get out of it. If this is your ideology, then calling what is happening in Muslim cultures oppression may be something you're not eager to do. You might think that the fact that you wouldn't want to live like these Muslim women is just a sign that you have been indoctrinated with western values rather than Islamic values.

Another ideology that may lead to people wanting to not say that something is going wrong in these cultures is religion. While there are many religious westerners that have no sympathy for Islam, there are many who recognize that their own religious values and traditions are under fire from current movements. If they say it is okay to take away one religions freedom of belief, it weakens the case that their own religious beliefs should be protected when they are at odds with societal goals.

These are just two popular ideologies, but there are many more that people could hold that may lead them to not condemn oppression of Muslim countries' treatment of women. Another big issue is that interfering with another sovereign nation is a complicated matter. We wouldn't want another nation to come over here and force their way of living on us. So the danger of setting a precedent of interfering with another nation on moral grounds, and making ourselves the moral authority of the world, would likely not go over well with other sovereign nations. Different nations need to encourage a live and let live policy when it comes to cultural differences. As a result, people often feel like it is more productive to focus on social issues in their own country than abroad.

So I think overall, it is not that people have chosen to just say that everything is fine with the oppression of women in Muslim countries. Rather, I think the issues is more that there is no general consensus about what to think about it and what to do about it. There are plenty who condemn it, but unless more people have a motivation to be against it, being against it is unlikely to become the "common sense" view in the same way that standing against anti-semitism and racism toward African Americans is.