Prostration as an Approach of Buddhist Practice
Prostrating to the Buddha is not merely a ritual.
Those who have never learned the rationale behind the proper way of worshipping the Buddha usually consider it the same as worshipping deities and it is alright to just bow with joined palms. In addition, they consider prostration an external form of worship, which is not important, and are of the opinion that they are protected from harm as long as they are sincere.
However, having a smooth journey in life is not the purpose of practicing Buddhism or worshipping the Buddha and Bodhisattva. In fact, we practice Buddhism to cultivate our mind, and prostrating to the Buddha is a form of mind-cultivation, not just a Buddhist etiquette.
Letting go of our attachment to self
The most difficult challenge in Buddhist practice is to overcome our inner self or our attachment to self, rather than dealing with the external environment or those around us. It is not easy to be humble and to let go of our ego. In letting go, we let go of our greed, anger, desires, and attachments. This is also the significance of prostration.
Paying respect to the Buddha through bowing with joined palms is a sign of respect; this, however, does not help to eliminate pride nor ego. Prostration, when practiced sincerely, enables us to let go of our ego and attachment to self. Hence, prostration is the proper way to worship the Buddha as it is a way to cultivate non-self in addition to paying respect to the Buddha.
50 Questions on the Practice of Prostration to the Buddha (拜佛50問), Dharma Drum Publishing Corporation