1.   If there is an explosion, the foam helps absorb the shock wave.

2.   Inexpensive, adhesive-backed foam weather-stripping can help stop air penetration at the bottom of a window sash.

3.   Sticky foam might help to capture intruders by blocking exits with large bags filled with the substance through which an intruder would have to pass in order to escape.

4.   The foam helps prevent sparks, and a possible fire, should the plane skid on the runway.