Let's walk this through:
Red and Blue: The Legendarys are just really rare pokemon. ok
Gold and Silver: The Legendarys are still pretty normal, but with a few legends involving them. cool
Ruby and Saphire: The Legendarys are Primordial god-like beings who shaped the earth. Ummmm....
Diamond and Pearl: The Legendarys are superpowerful, extra-dimensional gods who control time and space. Yeah..... It's like they could make a pokemon that created existence and everything. Oh, wait, Arceus.
I honestly don't see how nintendo can keep this up. I'm not really that angry, I just thought this was interesting to point out.