It's a better model because it's simpler and directly answers the question of where we came from. A simpler model that gives an answer with no evidence to back it up doesn't exactly work in the real world.
Because there's still no evidence for anything outside of the natural. In science, we have things that can be explained and things that can not yet be explain, but that we hope to find answers in the future by doing research. In religion, we have things that can be explained and things that God has done that no one questions. And no smart scientist will say that they will never consider creationism as science. They say that until some evidence is given, they have no reason to consider it. Imagine I went to a scientist and told him I could fly. Would he say "Oh wow! What an amazing discovery! This will go in all the science books!" or would he ask for proof of my claim?
And as of right now there's the same amount of evidence for both aliens planting life on Earth and God creating it. It's actually really closed minded of you to completely dismiss something like this. It's interesting how I look around and see all these Christians (not necessarily this forum) call people who believe in evolution "close-minded." Now look at your statement. Do you have any proof that this won't happen? Probably not, so why completely dismiss it? I'm open to every explanation. Yes, even that a God created it. Only an idiot would actually say "There is no god." Even some of the most famous atheists and scientists (i.e. Richard Dawkins [edit] has stated that it would be unwise to dismiss something that can't be proven to be untrue. With the current amount of evidence, I do not believe that there is a God, but it's certainly still a possibility.
Edit: Are we not allowed to post links to youtube vids here? I would have figured people would want proof that what I was saying was true rather than just stating something as fact with no evidence.