I think this is a better explanation.
"In Latin theology, the divine Persons were considered as the simple inner relations of the unique essence of the Godhead: hence, if the very existence of the Spirit is determined by its relations to the Father and the Son, the doctrine of the Filioque - or procession of the Spirit from the Father and the Son - becomes a logical, dogmatic necessity, for the Spirit cannot be said to be distinct from the Son if he does not proceed from him.
Eastern theologians, on the other hand, remained faithful to the old "personalism" of the Greek Fathers. The doctrine of the Filioque appeared to them, consequently, as Semi-Sabellianism (to use the expression of Photius). [Sabellianism is a heresy dating from the second century attributed to a certain Sabellius, who taught that the divine Persons are simply "modes" or "aspects" of a unique God.]
Consubstantial with the Father and the Son, because proceeding from the Father, the unique source of the Deity, the Spirit has his own existence and personal function in the inner life of God and the economy of salvation: his task is to bring about the unity of the human race in the Body of Christ, but he also imparts to this unity a personal, and hence diversified, character. It is with a prayer to the Holy Spirit that all the liturgical services of the Orthodox Church begin, and with an invocation of his name that the eucharistic mystery is effected."
And here, hopefully, you can see why this is so important to us. It is part and parcel of our entire liturgy, with the epiklesis we so strongly defend.