Hebrews 1 vs. 1
“God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets,” (KJV)
God never had one way of communication to our forefathers. He had diverse ways through which He communicated with them by the instrumentality of the prophets.
Ephesians 4 vs. 10-12
“He that descended is the same also that ascended up far above all heavens, that he might fill all things. And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers;
For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ:” (KJV)
Even after the ascension of Jesus Christ, we still have the continuation of the Prophetic ministry and the other ministries. The reason is for the perfecting of the saints; the nourishment and the upbringing of the body of Christ.
In these last days, the Prophetic voice is needed for the perfection of the saints.