There are many different reasons to suspend, from pure adrenaline or endorphin rush, to conquering ones fears, to trying to reach a new level spiritual consciousness and everything in between. In general, people suspend to attain some sort of "experience".Some people are seeking the opportunity to discover a deeper sense of themself and to challenge pre-determined belief systems which may not be true. Some are seeking a right of passage or a spiritual encounter to let go of the fear of not being whole or complete inside their body. Others are looking for control over their body, or seek to prove to themselves that they are more than their bodies, or are not their bodies at all. Others simply seek to explore the unknown.
Many people believe that learning how one lives inside ones body and seeing how that body adapts to stress -- and passes through it -- allows one to surrender to life and explore new realms of possibility. While some people are seeking something spiritual, others are just looking to "do it" and the sense of accomplishment is enough for them.