people have been able to watch television, play video games etc. Newspapers traditionally have not been sources of entertainment, although more recently pander to the lowest common denominator.
Nihilism as a branch of philosophy has been around for centuries. Nihilistic kids (who wouldn't necessarily even know what nihilism is by the way) but who nevertheless are poster children for the term, are much more recent.
The term morality can be used either
1. descriptively to refer to some codes of conduct put forward by a society or,
a. some other group, such as a religion, or
b. accepted by an individual for her own behavior or
2. normatively to refer to a code of conduct that, given specified conditions, would be put forward by all rational persons.
Religions by definition deal with the concepts of right and wrong and have been the traditional sources of education in what constitutes ethical behavior i.e. the 10 commandments. (I personally don't subscribe to any religion as I find them to be overwhelmingly hypocritical.) However the primary source of that information should be found in the home.
If people were more morally grounded, as opposed to being nihilistic, they would be less inclined to view life as something cheap to be wiped out, (both their own and others) when things are not going their way. They might even find the concept of using guns on other people morally reprehensible. A society of moral people has no need for guns. Instead, in the US, there is a proliferation of guns. Very soon the number of guns will outnumber the population of the country. The NRA's solution for gun violence is more guns - a kind of mutually assured destruction tactic. If that's not a sign of moral decay, I don't know what is.