I agree it's kind of silly to put forth a visual web demo and exclude 90% of browsers (especially when these same effects can be rendered in all browsers, with the proper browser-specific tweaks), but does there need to be a practical value? I think the point is "Huh. Cool." Demoscene for CSS. These demos are also good for putting new features/techniques through their paces.
I think this kind of thing is like a light on the horizon for web designers. It lets us know that some of the things we wish we could do now are at least going to be feasible someday...