I'll be brief. That means, "Don't get upset at me for not thoroughly discussing every facet of the topic."
I deeply appreciate good sermon illustrations, but think that illustrations should be used with great caution. They should be used to communicate ideas that might not otherwise easily connect with an audience, whether intellectually or emotionally. Preachers should think hard about whether their illustrations do in fact promote the reception of the message they want to convey, or whether they might actually divert attention from the message. A captivating illustration can easily distract a listener from hearing what the preacher continues to say after the illustration is finished (including the very association he was trying to make in the illustration). And if the connection with the point at hand is not clear and strong enough, the memory will discard what was difficult to understand in favor of what was more accessible.
Do you remember the last powerful sermon illustration you heard? Do you remember the point that the preacher meant to make by it? Or do you just remember a vivid story? If the latter, then the illustration failed its intended purpose.