Probably the reason that Buddhism is such a thriving idea is because that it has no central arbitrator, no limits, and no constricting rules like other religions. It also states that life does not end with death.  It says that you will be reincarnated intothe shape that is decided by your karma.  What I think what keeps Buddhists so involved with the religion is that the proposal that nirvana, a pure state that is desirable by all, is the solution for all the suffering that one would ever encounter.  I think the desire for enlightenment is the only desire accepted to be all right by avid Buddhists.  Many Buddhists, like myself, do not live up to the ideal of a pure soul who has no wants in the world and helps his fellow man at every chance.  My personal relationship with Buddhism has led me to think that it is for the dedicated few that would give all earthly possessions and spend their lives trying to achieve the grand prize, nirvana.   Though in my opinion, I do not think there is a single person who has no desires at all; desires make us human and to hold back desires is to hold back the very thing that makes us human.