Quick question, AE, as an aspiring GM, how in the actual hell are you keeping track of all these numbers without going insane?
Have you read the book Gamemastering by Brian Jamison? It's in the public domain, and a very good place to start.
Some gamemasters see a spectrum between storytelling and mechanical gameplay that devolves into board-gaming. Piecewise's ER strikes a very good middle ground where the numbers are important, but he doesn't let it get in the way of epic storytelling. The roleplaying in the nationstates and starwars combine forums are more extreme left, where the mechanics are more arbitrary but storytelling is emphasized and character development is rewarded. Dungeons and Dragons and other crawlers would be extreme right examples. I'm not experienced enough with stories, but I am very strong with numbers, so I'm leaning to the right with the modified ER system.
As for how I can pile on variables and still think it's the most beautiful thing in the world: I'm an accountancy student. A good accountant can juggle hundreds of spreadsheets in their head without a computer. I can also tell you how to clean money in completely legal ways...
Also, I like simulating reality. It's easy to visualize and quantify. Most the numbers I plucked are real, but I can make some small changes for gameplay and !fun!.