What's with the Gecko?

Alright, I know that this is a diversion from the World Cup theme on this blog, but I've had this nagging question in my head for weeks now, so I'll just blurt it out:

What's with the Cockney accented gecko in the Geico ads? Is the rhyming slang really a selling point with American audiences or are they just too damned cheap to change the voice from their British ads? On one of the recent versions, the silly lizard compares Geico insurance to "free pie and chips," and I can just imagine some gherkin in Omaha, saying, "Apple pie and potato chips - no thanks!"