The Buddha established the monastic community for a purpose. To overcome afflictions, we need correct wisdom, and to maintain such a view, single-pointedness of mind is essential. To concentrate, mindfulness and introspective awareness are required, and these are cultivated through training in ethical conduct.
The ethical conduct of monastics is stricter than that of lay followers and thus is more effective in subduing the mind. Whereas the life of a householder may be more colorful, monastic life is more stable. Although it is difficult and requires giving up sexual relations and so on, there are benefits even in this lifetime. The monastic way of life is praised because it has direct relevance in developing the three higher trainings.
This latter point is important, lest people think that the monastic life is outdated or irrelevant in modern times. Our Teacher, Buddha Śākyamuni, was a monk. The Buddha lived as a monk from the time he left the palace until his passing away—over fifty years. His ethical restraint and monastic lifestyle were natural expressions of the purity of his mind. So many great Buddhist masters also lived this way, and the examples of their lives convey to us the importance and benefit of monastic life.
However, monastic life is not suitable for everyone. People must choose the lifestyle most appropriate for themselves and have confidence in their ability to practice. A lay practitioner who practices diligently can attain high realizations. Marpa and his disciple Milarepa were highly realized lay practitioners, yogis, and teachers.