Sri Chaitanya initiated the taking of sannyasa, but not for the reason you may think. Previous to His action, the Krishna Bhakti community did not take the sannyasa order -- that order was the domain of the impersonalist schools of the Advaitans. The Vaisnava community was percieved by the Advaitan community as a sentimentalist , emotional form of yoga, beneath their perception of themselves as staunch yogis , severe ascetics, and sober intellectuals on the highest path. To them, the Krishna bhakta was almost beneath contempt, childish, and unable and incapable of understanding their comprehensive Vedanta.
So, Mahaprabhu took sannyasa from their lineage, went to their center of learning , and then displayed the very things they so abhorred: emotion and sentiment. His display was so moving, emitting such ecstacy, that the leaders of the sannyasa community of the Sankarites fell under His divine spell, eventually becoming his intimate devotees.
This would not have been possible unless Mahaprabhu took sannyasa. He would not have gained the intimate association of the leaders of the Advaitans, or engendered their respect and attention, if He had gone to them as a Vaisnava.
This, then, is the true purpose of sannyasa. It is for those who cannot accept the transcendental nature of Krishna bhakti, who need a severe ,ascetic representation of Vedic truth. Sanyassa was introduced for them. For the devotee, it is completely unnecessary, as this renunciation is a service for the advancement of the ignorant souls who cannot percieve the sublime nature of the Bhakti sanga.
It is for the fallen souls, to give them confidence in the authenticity of Bhakti, nothing more.