Emotions in psychology are the layer that connects neurochemistry, the simple neurological brain functions, and cognition that controls behavior and even our consciousness. Therefore emotions play an important role. They are affected by both the neurochemistry layer below and consciousness above. Emotions can buffer or enhance both of them. All our physical well-being and strength as well as psychological comfort and creativity depend on emotions.
As with biodiversity (the number of different species living on our planet) we use to think of emotional diversity as of something beneficial. Even higher animals, mammals in particular, show behavioral reaction comparable to human emotions. When we look into a dog’s eyes, we may read faithfulness. In a cat’s behavior, we may recognize self-will. Sheep unconditionally follow the flock. A fox is cunning, a wolf aggressive, and a lion majestic. Though parallels between humans and animals may be misleading, the major advantage of humans is manifoldness. We humans have a much greater repertoire of emotions available. The spectrum from which we can choose an emotional reaction is much broader, so we can react more appropriately. Usually.
There are risks of emotional deprivation though.
Loneliness or isolation. Emotions are like muscles they need do be used to maintain their function. If someone is deprived of interactions with other people emotions may dwindle. Typical examples are solitary confinement and the man living alone on an island, Robinson Crusoe.
Alcohol and other psychotropic drugs. Emotional deprivation is one of the first symptoms of chronic drug abuse. It often goes unrecognized or is even misinterpreted. In its final stage, drug addicts have but two kinds of emotional reactions positive (lovely, charming, laughing) when height and negative (fear, aggressive, reflex weeping) when down. There is no question that those who live with such addicts are of height risk of emotional deprivation, too.
Uniformity/monotony: living in perpetual fear or stress can lead to emotional deprivation. Uniformity is contagious in mass hysteria, religious ceremonies, and demagoguery. Some tools to deliberately initiate it are scary movies, monotone music, lockstep or even torture.
Societies: There are social groups in which emotional deprivation is welcome, in military for instance. Therefore recruits are drilled. Also, monotony, enslavement, and intimidation take place at many work places.
Senescence and mental disorders: With declining neuronal function also the spectrum of emotional reactions becomes narrow. Sometimes this process is even accelerated by antidepressants or other psychotropic medicine.
Of course, there exist ways to counter emotional deprivation to even enhance its diversification. Many gifted people devoted their life to just promote that.
Art, literature, music, performances: You may wonder why people started cave painting or decorating pottery. There was no practical reason for that. A drinking vessel can be filled and emptied regardless of whether it is decorated or not. The only difference that matters is the emotions that are caused by an elaborately decorated vessel. That this is an important issue can be learned from history. Over the centuries, the production of artifacts whose sole purpose is to cause pleasure increased exponentially.
Broadly based communication: An other tendency that can be observed in human history is that communication has accelerated. Just recently by the advent of social networks great progress was made in this direction. Communication with different people from different social and cultural backgrounds counters isolation and therefore helps to develop new emotions.
New Impressions: Provide the brain with new visual, acoustical, odoriferous and even tactile information performs what I use to call a “brain reset”. (Similar to reboot a computer.) New information that may bear such property include landscapes, flowers, buildings, performances to name only a few.
Creativity: As creativity depends on a broad spectrum of emotions, training one’s own creativity automatically enhances emotions. Scientific endeavor and other intellectual challenge is to the same effect.
Love: It goes without question that love stimulates and develops emotions. Not only love provides new emotion, but also it offers incentives to venture into new emotional territories. Musicians, poets and painters used to desperately deeply fall in love. For just that purpose I guess.