Well lets put it this way...expression web is meant for designers and it probably fares slightly better. But if your app grabs some data from a web service via AJAX and displays stuff dynamically, there's no "design view" on earth that can handle that.

Another way of looking at this is that "design views" aside, different browsers render the output html differently. How can one design view attempt to mimick the look of the final output? If everything is static, inline without javascript and little to no css, design view should shouw what the IE output will be, but even that fails most of the time. Again, design view is not a "preview mode".