In an ideal world, designing from the ground up, I can agree with many of Lazyboy's points. In practicality, I agree with the "Creator-based Lands" approach to DHS. It is the most cost-effective and realistic way to take what is at DHS and to give it a better semblance of organization and theme. This could be the Great Conceit of the Hollywood-based park: themed areas may be based on Great Film-makers (which could then be sub-divided into the fictional worlds created by those film-makers or left as the "Studios" where these movies were made). Another pitfall of "strictly-theme-ing" lands in DHS (e.g. Tatooine vs Lucasland) is that it fully erases any distinction between DHS and MK (which is more Hollywood-based now than ever).
To expand on the USO analogy: what if Men-in-Black were instead a "Futurama"-based ride. That area, coupled with Springfield, would flow nicely as they have the similar feel of Groening-inspired creations, despite time/space differences. One might group them together as GroeningLand, or just call them Springfield and Futurama. On a map, its just semantics.
And despite the obvious clear differences among them (time & space), Indiana Jones and Star Wars are filmic cousins: stylistically, tonally, cast-wise, etc.,. It might even be easier to imagine Indiana Jones and Star Wars sharing the same "land" than Star Trek and Star Wars.
The Pixar Films, the Jim Henson properties, the classic Disney animated Fairytales, the Universal monster movies, etc. are all filmic cousins, as well. This is why there is an opportunity to mix them together within theme parks (as with everything, it would come down to execution). I think there are plenty of ways existing areas of DHS can be creatively re-vamped to link the properties within more compelling environments, many variants of which have been brought up at WDWMagic. E.g., one could envision Mos Eisley transitioning into Cairo, linking two sub-areas of a Lucasfilm based-land. The Pixar Library would be easier to group in a land, as all but Brave and Wall-E, take place in quasi-contemporary, similarly-stylized worlds.