Okay, so I've been reading Kallistos Ware's The Orthodox Way, which I felt had a deep explanation of the consequences of the fall of man and why-- this is an explanation that I'll try to relay here, but I do recommend that book (though I haven't finished it yet): essentially, man's special because he was made in God's image, but is also special because he's essentially a microcosm of existence, bearing both spirit and physical body.

God isn't merely an infinitely big entity that exists either inside or outside of the universe-- He is the basis for existence. He is life. He is "good". This is acknowledged in the Trisagion Prayers, which addresses Him as-- among other things-- He who is "everywhere present and fillest all things".

With all this said, man was in perfect communion with God, but disobeyed God, and therefore fell out of communion with Him. Because God is life, we fell out of communion with... well, life. This is why God warned Adam and Eve that if they ate of the forbidden fruit, they were going to die-- it clearly wasn't "the fruit is poison" or "I'm going to strike you down if you eat this fruit". It was that they did something contrary to God's command, and in effect turned away from God-- we turned away from life through an act of sin, the wages thereof, it is written, is death. This is why we eventually die (I've read from someone-- I can't currently remember, though it might have been a Church Father-- that physical death is a divine mercy because due to it, we don't have to continue suffering through the continued physical degradation caused by our continued "excommunication" from God), and this is why until Christ, the souls of the dead stayed excommunicated from God. This state of being has been called "Sheol"-- or, as the Greeks called it, "Hades".

Alright, totally unrelated to the original question prompting this thread, but, do you happen to know whether this description/interpretation is shared by Catholics? If you don't know, or whatever, I'll just slink back into the shadows whence I emerged...