There is a principle of improv that says in order to draw an audience into the drama, each actor must take a "yes, and" approach. If one actor says that it is a cold day and shivers, then all the other actors must join in and build on that to create a realistic scene, collaboratively, on-the-fly. In short, it leads to better performances.

"Accepting an offer is usually accompanied by adding a new offer, often building on the earlier one; this is a process improvisers refer to as "Yes, And..." and is considered the cornerstone of improvisational technique. Every new piece of information added helps the improvisers to refine their characters and progress the action of the scene."

Wikipedia - Improvisational Theatre