Why an academic robe and a central pulpit?

Our heritage as Protestants is the Reformation in Europe 500 years ago, when God raised up those who led a return in the church to the Scriptures (Sola Scriptura) and the truth of the Gospel taught therein. We stand on their shoulders, and the calling remains ever to be the Reformers in our day.

The Bible preached became central again to worship, and priests with elaborate liturgical garb, who were often just appointed at the time to their positions, without training, were replaced with pastors, whose calling was to preach and teach, and who had to study and be examined before taking up their positions - a rigorous process carried on in denominations like ours to this day (thus the academic robe). 

And church architecture transitioned from a central "altar," and the focus on the observance of "mass," to an elevated central pulpit, with the Word of God, read, preached, and sung, the focus or heart of worshipping God in truth.