I think this is great for prototyping ideas. Using Photoshop for web design is an approximation at best.
I do both design and development and I find I use very different parts of my brain when doing one or the other. For me, it's important to stay far away from any kind of code until it's actually time to start implementing. Otherwise, I fall back to predictable habits.
We could build an entire product just trying to generate semantic, reflowable markup from a design.