Because for me, it's better than any trip could offer, I can watch it over and over again because, because, every bit of the show is layered like an onion (though one that will make you think involuntarily, not make you cry), therefore it's for the serious thinker, it wants to debate theism and open a dialogue with the viewer about metaphysics.
Its plot is very subtle and often ambiguous, allowing for multiple viewings over the course of the show. Is the alien guy just a midget in a suit, or is he a real extraterrestrial? No-one knows.
Just make sure it doesn't turn you into a gibbering catatonic like one of the side characters who doesn't know reality from internet, it has a serious mind BLOWING potential.
It has strong cyberpunk themes and visuals.
Serial Experiments Lain, Serially Interesting
