It's useful for acoustics, to help everyone hear what's being said - especially if you don't have a microphone. Jesus used a boat on the lake to help with the acoustics on at least one occasion. Like a natural ampitheatre, I understand, the sound would be reflected from the water so that everyone on the shore could hear.
I think Ezra's "pulpit" was a kind of scaffolding with a platform on top, similar to a stage. There were several other teachers up there with him, who explained and translated the words into Aramaic, so it must have been fairly roomy.
On the jokey side, of course a pulpit sets one "six feet above contradiction".
A probably apocryphal tale is of the preacer who was a real pulpit basher. He was preaching a hot hellfire sermon, and thumping the pulpit.
"I am coming down among you", says the Lord!
THUMP! BANG!
I AM COMING DOWN AMONG YOU!
BANG! BANG!
[size=medium]I AM COMING DOWN AMONG YOU!!!!
BANG! BANG! THUMP! BANG![/size]
[size=large]CRASH!!!![/size]
And the pulpit collapsed, and he did!
Jeannette