We are such social creatures that can even doubt about their personality and existence in the absence of interactions. It is not in the scope of my area to talk about the roots of our social behavior. However, it is clear that making interactions and connections were more beneficial for us than being alone.
In an economist point of view, I could mention that trade makes life easier for people and increase their well-being. The rational people would finally notice this and prefer to trade rather than making effort for all the items/services s/he uses. So that, s/he would consume more and be happier. As weak creatures, we need others for a better life, this makes sense of the importance of human interaction.
Even if the need for interaction may be partly because of the trade we do all the time, it seems like we have other reasons for this need. We do not seek only superficial connections, but also, we try to belong some group and make real connections. Need for affiliation is one of the 3 motives in McClelland’s Need Theory of Motivation. Even if, we all have different levels of need for affiliation, we all have the need to belong, make real positive connections with some people. How do we cope with the loneliness as a result of the culture which supports individualism in the 21st century?
Although the eastern societies are evaluated as having more collective cultures, dynamics of the cultures are subject to change in this era. People are getting more and more individualistic. It is getting harder to have close friends and even a romantic partner. As we get more individualistic, we get less tolerant and empathize less. Does this individualistic point of view help us at all? Can we be happier with this attitude? Individual may value himself/herself more than others. However, without belonging, which success may make us happy? If you do not belong to your work, friends, family or maybe your partner, how could you be happy?
Balance may be the key here. You should be individualistic that you value your self-interest, and you should be collectivist that you belong and make real connections. I am aware that it does not sound easy at all. However, life may not be mechanic as some of us (including me) thought. Even if we have a utility function, need to belong, and need for affiliation may be a crucial part of it. Do not underestimate our human-side!