What kind of design? Poster design? Graphic design? Industrial design? ... Web design?
> designers with no previous web development experience
I don't want to sound elitist, but I would argue that designers should learn about how the web works, or they're not qualified to design for the web. Issues like pixel-perfect vs flexibility, the constraints of a browser vs the freedom it gives to a wide audience. The fact that it's not just for able-bodied people using off-the-shelf browsers.
If designers can learn all about typography and layout, they can surely learn about DOM and CSS (or some sub/superset). Even if it's a bit messy.
> in a code free environment
Knowing the mental model is not the same as writing code. I've worked with some great web designers, and the ones that produced the websites that looked, felt and worked the best were the ones that could prototype their designs in CSS.
I've only had a brief play with this, and it does look very cool. But you can give a non-developer a good experience by creating an explicit and mental model that reflects the model of the web. The "content" view does look like it has a well thought-out consistent hierarchical semantic model (i.e. not just smushing lots of things onto a page). But if it isn't a superset of the Document Object Model, you're going to be fighting the browser, not working with it.
If you're doing this, you're on the same trajectory as designing in Photoshop and exporting image maps. Or Making Macromedia Flash sites. Or distributing pages as PDFs or PNGs.