Oooookkkaaaaaaaaaaaayyyyyyyy......
I think there's some confusion in terms here.
CMS: Content Management System - meaning, it's a tool to manage
content.
Developer: person who writes the underlying code.
Design: decorative scheme; composition - meaning, it's the front end "pretty" that the visitors see.
The CMS should be used as a tool to make life easier on both the designer and the end user. Nothing more.
You're still going to have to design the templates yourself, you're still gonna have to markup your own code (unless you use dreamweaver) to display the output from the underlying CMS.
It's the backend that's going to change, usually for the better (unless it's postnuke), to allow your clients to update their site on their own. And usually, without having to come back to you for minor changes.
Don't confuse the CMS with the design. They are too separate beasts that, when used
together can make for one great website.
Default CMS templates all suck. And I mean it in the most affectionate ways.
But they are intended to make life easier on the end-user. Which they do...unless it's postnuke (except postnuke). It's just a matter of finding which one would work best for your (or your clients') needs.
If you don't want the hassle of becoming the developer, and don't want to write the underlying code, but want your own creative designs, by all means, give the CMSes a try (except postnuke). However, if you like more control over you code and how it outputs, you ought to look into writing your own backend.
PS: have I mentioned how much I hate postnuke? 