I would error on the side of making something more useable than beautiful. If something is ugly, but still usable, it has value. If something looks good and is not usable, it doesn't have much value. Unless it's Art or something that is only meant to be looked upon.
On the eCommerce projects I've worked on, a "conversion" was defined as a user simply making a purchase. So the goal of any of our designs was to make that action happen as often as possible (in as high quantities as possible). At the end of the day, it didn't matter if we personally hated a design, or if we thought it was ugly or anything like that. The design that made the most money was the best design.
Now that task could be range from buying a faucet to seeing when your favorite band is in town. The easier it is to accomplish the task, the better the website.
