The importance of developing the unselfish emotions can't be over-emphasized. As I have said previously, the development of unselfish emotions helps to develop the Right Intention which is the foundation of Virtue. Right Thought or Intention is the second factor of the Noble Eightfold Path. There are four unselfish emotions and they help to balance each other.
Lovingkindness by itself without being supported by Compassion, can be unbalanced and light. Many people feel that if they just develop Lovingkindness it will enable them to have the Right Intention towards others, but without compassion or wisdom, we may not be able to change our view of others, especially difficult or hurtful people. Without the deeper transformation of the selfish view into the unselfish view, i.e. understanding the Dukkha of our subject, we may not be able to wish them to find peace or contentment. When we are able to contemplate the Dukkha these beings may have, compassion can arise and this gives rise to the lovingkind wish that they will be able to lessen their Dukkha and find peace. This enables our Lovingkindness to be less conditional.
Some people believe that we don't have to practice Compassion or Lovingkindness, because it will "come later." Why wait? And that's just a belief, anyway. It may never come "later."
Development of Compassion and Lovingkindness is extremely important because it forms a basis of spiritual happiness. Unless we develop an emotional spiritual happiness, it's very difficult to let go of a deep attachment to worldly happiness on deeper levels, because we haven't got anything to replace it.
When we look around the world, everything is unstable, impermanent. Most people are seeking their happiness based on these unstable, impermanent things, i.e., "happiness comes from getting this"; "happiness comes from getting that". But to obtain this type of happiness depends on many things that are beyond our power to control. But a happiness that is more dependable comes from giving, and Compassion/ Lovingkindness is a skillful expression of giving. It's the basis for skilful Generosity as well. It's the giving of our heart, the giving of our good wishes, unconditionally. Not wanting anything in return.
We may gain insight into how the power of Compassion/Lovingkindness helps us to let go of selfishness, and selfishness is a cause for Dukkha for ourselves. The unselfish emotions are the basis of skillful living. A long time ago I asked Mae Chee Ahmon about the importance of the, and she said, in the Thai culture, one is not even considered to be a human being until one has a foundation of this. They have 2 different words in Thai: "kone" and "manoot." "Manoot" means a mature adult; a "kone" is just a regular person. She said, in order to be a "manoot," you have to have the foundation of the unselfish emotions. That is maturity.
In Thai culture you're not considered very mature unless you have some Lovingkindness. It's not usually a requirement for being mature in the West! They're more devoted towards material security, whether we have "enough" money or status.
Lovingkindness is extremely important for letting go of fear. Fear in most people is very agitating. Fear of blame, praise, the 8 worldly conditions. If we have a heart of Lovingkindness, we'll be less afraid of people. Not afraid of their blame or their praise or censure or whatever, because we're not depending on them to give us happiness, we are not seeking to Brahma Viharas get something from them. With less expectations there will be less fear of not getting what we want from them. The unselfish emotions help build more confidence. With a moral attitude of giving we have a better intention. If we have better intentions, then when we meet with blame or whatever, we try to remember to look at our good intentions, and if we see there is no cause for blame, then it is more possible to leave the blame with others.
The dangers of developing Lovingkindness? It needs to be balanced and supported by Equanimity and Wisdom. Occasionally people may think that because I teach Compassion/Lovingkindness then they can get anything from me. So if we go too far on the side where we think Lovingkindness is always the gentle, giving, loving-type face, then we may not have the strength to say "no" when we see it's appropriate. True Compassion/Lovingkindness often has to say "no" and draw the line.
Developing Compassion and Lovingkindness doesn't mean that we're going to become weak. People are sometimes afraid that if they develop Compassion and Lovingkindness, then they won't have any strength left. "People are taking advantage of me already, if I develop Compassion for them they're going to walk all over me! I'll become a doormat!" But, we're not talking about a Lovingkindness that allows others to just do what they want to you. This is actually not true Lovingkindness for ourselves or them. They don't actually learn that their unskillful actions and speech will bring results to them, so if we have true Lovingkindness for others we learn how to draw the line.
We need Wisdom supporting Lovingkindness, otherwise it can become weak. Wisdom supports Lovingkindness so it doesn't become a "giddy" Lovingkindness. Lovingkindness can get "giddy", because it brings a lot of happiness. We may wish everybody to be happy as a way to try to avoid Dukkha in the world. "Love and Peace." We have to see both sides of the world, so that Lovingkindness is strengthened by Compassion and Wisdom, so it becomes a more mature Lovingkindness. If the four Unselfish Emotions are balanced between themselves, and supported by Right View, I don't see any danger in developing more and more Lovingkindness. The Buddha once said to his monks that if a person, for a snap of a finger, was able to feel true Lovingkindness for others then they are worthy of being a monk. So, the Buddha actually encouraged the development of this mind-state.
It helps with letting go of attachments. It helps with Renunciation, because when we have more inner, spiritual happiness, it's easier to give up the other types of happiness, which bring difficulties for ourselves. It becomes a basis for natural Renunciation, because we have something better. It's not like someone's going to come up and take your tricycle away, and you get very up set because your happiness is taken away. They come up and give you a 2-wheeled bike, and you see you have much more freedom! You can go to more places.