I think they need to make clear the concept of what an elemental really is before dealing with their planes. What is an earth elemental? Is it an animate piece of rock that just really likes being a rock? Is it a spirit of earth, tied to a specific location? Is it an earth creature whose personality is shaped by the connotations we give to the earth (stable but static, strong, immovable, stubborn or whatever else you can identify as an earth characteristic).
This will help define the planes themselves. If elementals are spirits embodying elemental features, then the planes need to have loads of them (no massive plane of near-solid earth since if so, how do you separate features on it for the elementals to embody). If they are philosophical analogs to their element, then elements should be as pure as possible.
The Inner Planes are supposed to be the planes of matter. Perhaps the best option would be the very first one; elementals are just animate elements with no instinct beyond being immutable and maintaining their surroundings pure. But that just goes against the planes having any features and certainly against outsider races on the Inner Planes who have different agendas. If Akadi wants the Plane of Air to be pure air, undiluted by anything, he'd be hostile to the djinn, wouldn't he? Yet his relation is neutral at worst.
A final issue is the gamist perspective. I agree that the Inner Planes as a grind (prepare the proper spells and maintain them or die!) are damn boring. . .
P.S. Personally I prefer the Elemental plane like the elemental chaos sans the Abyss and Limbo parts. A varied environment with realms of pure elemental matter in it. Limbo after all really needs a redefinition beyond chaotic elemental plane; that just is not as chaotic as Mechanus is orderly.