Why??? I mean, it's not a beautiful zone, because it's not meant to BE. It's supposed to look like a barren wasteland, and i think it does the job pretty well. The dark atmosphere, the lightning effects... You feel really alone here. I'm the only that likes it? I'm playing this game for the first time, and if people say Agon Wastes is the worst zone in the game, then i can't wait to see the others! I also find the Dark World really neat, that purple sky (which reminds me of Netherstorm from WoW anyway) is beautiful, and the whole atmosphere gets me so much that i would like to get the final suit just to explore it freely. It's a shame that it's so small compared to' the Light World imo.
One more thing: Why the Metroids are Red in this game? They were green in Prime.