There is so much dubious thinking here, it is hard to know where to begin. First, the age of melancholy? In Europe, happiness has been slowly inching upward pretty much all the time since they started polling people about that. In America it is stagnant or sinking slowly, but still not back to the bad old days in any way.
Furthermore, depression was underdiagnosed in the past. If you were hungry or overworked, it was only natural that you were unhappy. If you were neither, nobody wanted to hear you whine or watch you mope. Even suicides were often filed under some other cause of death so the relatives could have you buried inside the churchyard instead of outside. Unless you were famous enough that everyone knew about it, of course. Painters and poets seem to have been as depressed then as now.
Next: Computers don't cause materialism. If there were no computers, advertisers would try to wring your money from you with something else. Materialism is a big topic, but trying to tie it to computers and mobile phones is just insane. Lack of spiritual practice is a choice. If you get so many phone calls, turn off the phone before you start meditation or prayer. It is not like you had more peace and quiet when you lived with 8 other people in a small house. Even Jesus had to go out in the wilderness to pray. Turning off the iPhone is rather less strenuous.
The myth of social media replacing face to face contact - is that one still alive? If anything replaced that contact, it was the TV. Visiting people who just stare at a box is not motivating. In contrast, most people have the decency to log off IRC if they have guests. Or perhaps they just don't want to be seen cybering. In any case, computers over television any day.
In any case, you may want to come up with a theory that works for Scandinavia too, since we have more mobile phones than the US and about the same number of computers.