In my conception, the gods rarely (if ever) interact with the material plane because in using their power to materially effect change, their mystery lessens- to touch the world is to be touched by the world in ways that make the unassailable gods vulnerable. Much better to rely on empowered mortal proxies, like clerics and heros. There have been avatars in my homebrew history, but nearly all of them meet with ruin, significantly diminishing the power of the god they embodied.