Because it's not necessarily a part of all modern cultures. For example, pornography is illegal in many Islamic nations and can be difficult to come by, both online and in real life. In such a culture, the extermination of pornography would have a relatively minor effect on society, making it disposable.

Pornography is not difficult to come by in Islamic nations nowadays (if Pakistan is any indication). Its sold in the same places as other pirated western DVDs, often without the shopowner even realizing that it is a substantively different sort of thing compared to "normal" Western movies, which also tend to feature scantily clad women on the cover. There are also internet cafes with fairly unfiltered access to internet pornography and private rooms.

Pakistan, as a (nominally) democratic nation, is probably not the best example of your average Islamic nation (most of which do not possess democratic forms of government).

In any case, my familiarity with non-Western cultures is rather limited, and therefore I didn't want to unintentionally comment on any others in my initial post.

When you say "islamic nation," are you referring to one with majority islamic citizens, in the same way that britain, america or sweden are "christian nations," or are you referring to islamic theocracies?

It seems you are referring to the latter, but you should be careful bandying around such terms. There are highly secular democracies with muslim populations, such as turkey.

Since I considered Pakistan to be an Islamic nation (as I stated in my previous post), I was clearly using the former definition.

And while it is not impossible for Muslim-majority nations to be secular and/or democratic, it's highly unusual. Moreover, going back to the origin of this discussion, even in secular Turkey, the recent conservative movement there resulted in the banning of pornography in 2004. If you know Turkish, you can read the law yourself here: http://www.tbmm.gov.tr/kanunlar/k5237.html

It's not unusual for a Muslim-majority nation to be secular and/or democratic. It seems odd to go just be the number of countries and disregard the population size. Population-wise, the largest of those countries are Indonesia (pop. 228m, 86% Muslim), Pakistan (172m, 97%) and Bangladesh (162m, 89%). Even if you do go by the numbers and give Bahrain (1m) the same weight as the large countries, the word "secular" pops up often in the list at http://en.wikipedia.org/wiki/List_of_Muslim-majority_countri...

Well to give another example, pornography is illegal in China.

Making something illegal seems evidence for it being indispensable to many people.

If there were no demand or supply, why make the law?

Making it illegal suggests indispensability. Why make a law for something for which there is no demand or supply?

You suggest exterminating pornography would have a minor effect. If so many people want to exterminate it that they make it illegal (I suspect without checking that at times illegal under draconian punishment) but it still hasn't been exterminated, that seems another argument for indispensability.

But these points are irrelevant to my original question. Why specify Western culture?

Even if pornography were dispensable in some Islamic cultures (whether we label them as Western or not), that doesn't say it isn't also indispensable in non-Western cultures or dispensable in some Western cultures or both.