The interface for a typical elevator is still based on physical buttons that allow the user to select a specific floor, hold the door open, close the door, or ring the alarm bell. With the price of flat panel displays dropping, it is possible that in the coming years we will see touch screen LCD panels replacing the existing designs.

What are the advantages of completely replacing an entire typical elevator button panel with a touch-screen LCD panel?

What are the disadvantages of that complete replacement?