Also Web Dynpro technology is probably not the center of discussion here, IÂ´d like to add that it already integrates fine with Dev Studio but it also produces just a bunch of clientside scripts.
I cann only speak for EP. And yes, it uses a lot of client side scripting, but only if you did configure it so.
Ragrding the browser diversity. Yes this is problem, our solution is to detect the user agent and to adopt styles and scripts to the browser version.
And yes it could be also a desirable feature of EP and WebDynpro to have a configuration without scripting at all. You could create a feature request for this.
There a lot of new and interesting browser architectures right now in development at MS and Macromedia. Hopefully we will se a new generation in some years.