In its broadest sense, a pulpit is a raised platform from which a sermon is delivered. So, perhaps, my periodic grousing about preachers who leave (or never enter) the pulpit for the sermon is technically overbroad, unless he or she is wandering among the pews. There are plenty who do just that. At its root, my concern is for the protection of both the proclamation and the preacher. The risk is that attention will be diverted from the Word to the person.
Certainly, the tub- or desk-like structure I usually picture as a pulpit has no Biblical claim as the only appropriate place for preaching. Ezra preached from a platform with a praise team of thirteen (Nehemiah 8). Christ sat in a synagogue and even in a boat. In the Early Church, homes used for worship often had a seat of honor, a natural location for proclamation. This seated preaching continued from a basilica's seat of authority, adopted by Christians as the cathedra,
The practice of standing in a discrete, raised location may have developed from the ambo in the basilica and the bimah in the synagogue. The point is that through thousands of years of worship, a place has been recognized as set aside for preaching. Whatever the configuration, both the preacher and the hearer are somehow transformed when this place is occupied. At best, both know that God's Word is emerging, in a mysterious and sacramental act.
Is this irrelevant in more relaxed, less traditional worship? No, I think it may be more important when worship is less "set apart" from other kinds of gathering. It is a gracious practice to signal that preaching is not friendly advice or inspirational exhortation. Properly understood, a pulpit does that.
I admit that Joel Osteen demonstrates that proclamation of the Word does not emanate automatically from behind a pulpit-like structure. However, whenever the people gather before God in spirit and in truth, preaching from the pulpit is a sacramental act in the sense that it is both symbol and substance.
I meander around pulpits a bit in the May feature on my website, The Shadyside Lantern.