I recently facilitated a 2-day staff retreat.  I opened both days with icebreakers and put out a mix of art materials in the middle of the table around which the group sat. 

One of the group asked me why I used games and art supplies.  I was surprised, because I've been in training, retreat, staff, and planning sessions for many years in which icebreakers were always used, and while I first experienced the utility and pleasure of playing with clay and pipe cleaners in a retreat led by Stephanie Clohesy, I've seen art supplies in more and more meetings.  But it was useful to have say why.

Icebreakers help groups ease into what can sometimes be stressful work.  They help raise energy and generate a lightness that is a good place from which to begin to think together.  They can be an opportunity to for those participating to get to know one another -- particularly helpful for newer group members, and to the facilitator.  I also use them to help me get through the start-up jitters, to get a little bit of a read on the group dynamics, and I try to use what I learn about people in other parts of the meeting. 

As to art supplies, I put them out because they have a funny way of helping people think/feel/know what they think and believe, can leaven a heavy moment, and offer something to do in the more boring or anxious parts of a conversation.  They offer distractions without detracting.  Their use is entirely voluntary and some like them more than others.  The person who asked why I brought them was among those most actively using them.