I agree that when a man is called of God to be a preacher that Bible School (whether it be college or institute) is not necessarily part of God's plan for that individual.
This does not necessarily negate the school either.
Many "lay people" (for lack of better term) benefit greatly by Bible Institutes since they can learn more information at a faster rate than by only attending the 4 services a local church can offer (SS, Am, PM, Wed.) This is the whole reason many churches start Bible Institutes - to further obey the command of Scripture to teach.

Many people go to Bible college to further increase their knowledge of Scripture (which is a Scriptural command), and in the process are called to preach.

So, Bible Schools are not absolutely necessary for preparing a preacher, but are in most cases used by the Lord to prepare them. The preparation is much more than academic study. This preparation also includes: leaving home, living by faith (having to pay that school bill and support a family on low wages), serving in a local church (most Bible colleges requires some sort of service), etc. The Bible School experience is an education in and of itself.

That being said, I also believe that the day is coming in America when the local bible-believing churches will be forced underground, and then days of big Bible Colleges will be gone. The ideas we see today are truly an American luxury not seen on such a large scale at any other period of Church History. It truly is the job of the Local Church to train young men for the ministry.

In Christ,