I had never thought of the Evangelical Counsels as protection. Against what can they protect? Even today Our Lord recommended the young, rich man Poverty in order to tend towards perfection (Mt 19:21). Of course, Our Lord has never recommended anything that He Himself hadn't embraced. However, as Jesus said, following His commandments already opens the doors of Heaven to us. Yet, He proposes something extra to be perfect. Although we are creatures, the Lord, Who is all-perfect, calls us to the same perfection, as Our "Father in Heaven is perfect" (Mt 5:48), to "be holy… for I AM holy" (Lv 19:2).
In striving to be more like Jesus, it seems that St. Clare climbed a mountain where the fowler would not lay his snares so easily. As though the Evangelical Counsels set up a perimeter that the enemy dares not trespass. According to Scripture, the enemy doesn't want to have anything with Poverty, Chastity and Obedience. Conversely, Jesus doesn't want do have anything to do with the wealth of kingdoms, or with the lust of abundant food, or with tempting the Father (Mt 4). The Evangelical Counsels do raise a wall too tall for the enemy, as Jesus demonstrated.
But if the Evangelical Counsels perfect something, it has got to be the work of grace in us, the life in the Spirit through the infusion of the Theological Virtues of Faith, Hope and Charity at Baptism. Since the exercise of these virtues are necessary and sufficient to enter Heaven, Jesus however calls us to live Faith perfectly through Obedience, Hope through Poverty, Charity through Chastity, just like He has done since ever.
When Jesus calls us to be like Him, it certainly is not something that we can do on our own. He Himself told the young man to follow Him after embracing Poverty, because in itself it is naught. The Lord will complete the work provided that we say "yes": "fiat mihi secundum verbum tuum" (Lk 1:38).
Jesus became man so that men can be made divine, to be welcome not only to God's Kingdom, but before Him, face to face.