Colorful speech requires more brainpower

When speaking is a mere recitation of data, it's mostly your left brain hemisphere doing the work: That's where your speech centers are.

But once you start speaking in idioms-- and by extension, metaphors or other colorful variations--- your right hemipshere kicks in, too, along with your limbic system (the root of emotion).

One might say the craft of speech resides in the left brain, but the art of speech involves both sides.

Interesting study:
http://www.physorg.com/news172177545.html