I don't take it for granted at all. In fact, to find another earth, you aren't just finding a rock in some sun's temperate zone. The earth has the ionosphere, plate tectonics, and a moon that's huge in relation to the earth's size. To mention a few things.
The moon alone is a biggie. No other planet we know of has a moon as big (in relation to the planet). It strongly affects the tides. 4B years ago, it was way closer and the tides were like giant tsunamis - a serious kind of stirring things up in our oceans. The moon also keeps our precession from turning into a radical wobble that would cause violent weather pattern swings, from freezing to tropical, over very short periods of time. The Earth also rotated very fast on its axis before the moon was formed or captured, and the moon slows us down to the nice 24 hour rotation we have today. It also is a pretty big target for asteroids, meteors, and comets... Another factor is we have a huge Jupiter (and Saturn, too) far from the sun to protect us from those things.
The temperate zone is another big factor. If earth were just a little closer to the sun, the oceans would boil off. If a little further, the water would freeze over. There's not that much room for error.