You have to reach out to an audience on their terms, in their language. Metaphors help them understand something new in terms of something familiar.
Focussing on your main point -- distilling the essence and leaving out the details -- isn't inaccurate or misleading. It's like the a title, subtitle and abstract that precede a long article. For those interested, the details follow.
Consider these quotes:
David Roberts, a staff writer for Grist, put it best:
"The language of science is notoriously poor, not only at generating urgency and action but even at generating understanding. It's just not a language most people speak or understand. It's a specialized way of talking.
There is, or should be, nothing wrong at all in communicating with the public in the kind of language people do understand, the language of metaphor, analogy, and parable, the language of imagery and association, the language of values and meaning.
Doing so is not "inaccurate" and it's not a political liability. It's just common sense."
from "Talking with Andy Revkin about Climate Communication." Grist, March 14, 2011.
Finally, this excerpt on simplicity, from Made to Stick, by Chip & Dan Heath, the "sticky messaging" gurus:
How do we find the essential core of our ideas? A successful defense lawyer says, "If you argue ten points, even if each is a good point, when they get back to the jury room they won't remember any."
To strip an idea down to its core, we must be masters of exclusion. We must relentlessly prioritize. Saying something short is not the mission — sound bites are not the ideal. Proverbs are the ideal. We must create ideas that are both simple and profound. The Golden Rule is the ultimate model of simplicity: a one-sentence statement so profound that an individual could spend a lifetime learning to follow it.