No matter how perfect your site navigation is, some users won't understand it. They don't even want to learn it.
For those users, a search box is paramount, because that's the primary way they use the web. To them search is navigation.
Rather than exclude those users from your site, add one of our bespoke search box's. Rememeber, It doesn't hurt the usability or appeal of the site for people that don't use it.