The performance of steel comes to the fore with multi story buildings. It is light weight and its strength means that it can span greater distances.
Often height is the governing factor for multi story buildings so reducing the depth of floor beams can reduce the cost of the building or allow for more floor area with the same height.
A common trick is to cut holes in the beam webs so that services and ducting passes through rather than under the beam. This alone can take metres off the building height.
The University of Auckland Business School shows what is possible with optimised welded beams and a bit of imagination.