WHY DOES THE CHURCH MAKE IT AN OBLIGATION TO PRONOUNCE VOWS?
Why does the Church make it an obligation to pronounce vows, which are so like oaths? Saint Peter swore that he would give his life rather than betray Jesus. To take an oath like he did seems to be a sign of pride.
Vows are not oaths as expressed in the question. A vow is a deliberate and free promise made to God, concerning some good which is possible and better (Can. 1191ss). A vow is an act of devotion in which the Christian dedicates himself to God or promises him some good work (Catechism of the Catholic Church, No 2102). The Tradition of the Church, far from condemning such a practice, always praised it. Religious and other consecrated persons pronounce vows in order to better live out the Gospel.
Vows may be private or public, solemn or simple. A vow is public if it is accepted in the name of the Church by a lawful Superior; otherwise, it is private. It is solemn if it is recognized by the Church as such; otherwise, it is simple (Can. 1192).
Saint Peter failed to keep his promise to Jesus that he would not betray him; and he repented. His weakness, caused by a certain pride in his own strength of character, does not weaken the value of legitimate oaths, nor of vows or promises made freely, with Gods help.