Greg Costikyan wrote I Have No Words & I Must Design way back in '94. Now, this is pretty old, but I imagine some of the people reading this haven't read it. In particular, I think the color and simulation sections.
"The rules do nothing to evoke the Burroughsian wonders, the pulp action thrills, the Kiplingesque Victorian charms to be gained from the game's setting. Despite a clean system and a detailed world, it is curiously colorless, and suffers for it."
I've said it before, but your game should support the color of what you're doing.
"Or take Star Wars: The Roleplaying Game, which I designed. I could have taken Gygax & Arneson's Dungeons & Dragons and changed it around, calling swords blasters and the like. But instead, I set out to simulate the movies, to encourage the players to attempt far-fetched cinematic stunts, to use the system itself to reflect something about the atmosphere and ethos of the films."
This is pretty funny, because after WotC got control of the Star Wars license... They pretty much did exactly this. Which ties into my point: Using one thing to do something else sucks. It's not a good idea. Sometimes you don't have any other options, but...
It should be avoided. I don't agree with the trend of using D20 to do everything. I also think it'll pass.
Any comments on this? Feel free!