Yes and no, some of our top converting paysites are pure hand-coded HTML that i did myself $0.02

The problem comes when you start wanting to work with affiliates, more often than not program owners go the fancy design route because if they dont, affiliates wont send them traffic, even if the site converts like crack in a whore house.

We have a site that is retaining at 66.67% right now after the 3rd billing cycle and selling like crazy but i know for a fact no affiliates would ever promote it because the tour is to basic for them, of course the plus side is that all the sales revenue stays in-house

Regards,

Lee