After President Morgan Clark bombed Mars, Captain Sheridan used Draal's holographic system to announce all about the station that Babylon 5 will join other Earth colonies in declaring independence until President Clark is arrested and rightful government is restored.
Did anybody use that holographic system later?
It would be useful for other announcements. It can project images and sounds directly into the B-5 space station orbiting Epsilon-3, so it should also be able to project into spaceships orbiting Epsilon-3. That would be a useful tool to confuse enemy spaceships! I don't think anybody used that holographic ability again. (I am not sure Susan Ivanova used the holographic abilities when she broadcast reports on the atrocities of the Clark regime from the station's War Room. Seems like she used the Great Machine for signal boosting rather than for projecting holgraphs.)