It could work well if tabs contained frames instead of buffers, i.e. as a sort of workspace management. I guess this could be done right now by using a tabbed window manager.

I actually think it could work well if you could choose one or the other. aquamacs outlines the paradigm that I would generally use (frames usually equal buffers, but a tab can contain two buffers in necessary, like you often do in org-mode). I'm glad emacs doesn't ship with a tab paradigm by default, but it's easy enough to add one if you need.