RTF is a global modification that replaces all towns in the game.

More elementals – straight to hell :)
An elemental is a faceless and characterless unit, a universal filler. Their best role is as neutral creatures, because that way they don't spoil the factions with their presence.
A dwarven dragon, gargoyle, or djinn are exceptions, because they have their own identity, and elementality is a secondary characteristic. You can't say the same about the Luminary; it's some kind of pompous firefly, in my opinion.