Two words. The experience. Whether one believes that this benefit of experience comes in the form of knowledge or the benefit comes from just BEing, it is a reason to justify any incarnation.
An example of Experiencing for BEing:
The worlds greatest rollercoaster is opening up somewhere. You have saved your money to go to his park to ride this rollercoaster and when you get there you experience the moment of what is is to ride that rollercoaster. The amusement park will not allow you to bring this rollercoaster home nor is it practical to build a house next to this rollercoaster but you have put the effort forward to accomplishing your desire. Can you come back and ride the rollercoaster? Anytime that you want.
An example of Experiencing for Knowledge
Brian L. Weiss is a prominent psychiatrist and the author of Many Lives, Many Masters. Upon helping his patients overcome certain fears, anxieties and phobias he had stumbled upon the past life regression in a way to help people identify with their fears and overcome them. One example included a woman named Catherine, who visitied him for anxiety attacks. When the author could not find a probable starting part for her fears he tried hypnotic regression and realized that her concerns did not stem from this lifetime but from past lifetimes. After a few more sessions and understanding about where these anxiety attacks originated, Catherine no longer has these panic attacks and does not required the need for anymore therapy sessions. Dr. Weiss believes that we can learn a lot from our past experiences to explain why we react to certain situations today or why we follow certain interests so compassionately. He also believes that we can discover this knowledge for ourselves. He has written many books on the subject and presents a very interesting argument to support that many people have lived many lives.
FAQ
Does everybody reincarnate many times?
No, reincarnation is not a requirement to existing and in some ways there are tale-telling signs of how many times someone has reincarnated into a particular existence. Some people have never incarnated into a physical existence or have only incarnated once.
Why do we forget when we reincarnate?
The previous knowledge of our past lives may not be relevant to this one. One can compare it to the reason why they do not pass out movies scripts to read in theaters before the start the film. Very rarely are the cases where someone remembers glimpses or large parts of a past experience but they do exist and have been documented.
Is there are karma system implied?
There is no distinction of living a good, bad, long or short life that can be applied to your next decision to reincarnate. Though a planned purpose can be arranged with other souls there is no Godly measure of justice or penalty applied to your next incarnation.
So if I live a bad or poor life I wont come back as a bee or some kind of sea plankton?
You come back as a bee or sea plankton because you desire the experience. There are many factors why someone may incarnate into a physical existence. One consideration is the experience and another may be how long an entity wants to spend in a physical existence.
So God does not will me to an incarnation?
If God had chosen and planned your existence and purpose in a physical existence it would not be your purpose, your experience or your life, it would be a puppet's life and one cannot incarnate into an inanimate existence. An example of this could be a person who visits a travel agency to make plans to go on a vaction to Hawaii but the travel agent insists that the customer wants to go to Ireland. Why would a travel agent want to send you on a vacation where you wouldn't want to go?
Are there other physical realities to incarnate into?
Yes, BEing human is not the only possibility. There are many other species that one can reincarnate into and each experience is valid. There are even other locations and entities besides this planet Earth.