Anyway, I'd say the answer to having the being not interact with the heroes is the one Lee & Kirby already came up with: the herald, the intermediary who speaks on the behalf of the cosmic force. This is what ST:TMP did by using the Ilia Probe as the "voice" of V'Ger, and it's what TNG did by using Locutus as the voice of the Borg. That way you get to have it both ways -- the cosmic menace is still immense and above us and we are as ants to it, but there's still a character the protagonists can engage with and learn from. (For that matter, the idea has abundant mythological precedent -- gods have avatars and prophets that they use to communicate with humans rather than speaking to us directly.)
So arguably if you have the Silver Surfer, you don't need Galactus to speak directly to humanity, at least not until extraordinary circumstances draw his notice (e.g. Reed getting his hands on the Ultimate Nullifier).
