Rosetta Stone is bad and so tends to be every software tailored to softly teaching you a language instead of relying on your own will and effort.
I bet you that a lot of people, especially most of those who have reviewed Rosetta Stone, would disagree with you on that one. It may or may not be the best way to learn another language, but even if it's not, it's still much better learning that way than through memorization, translation, or drills.
Also, you're not 3 years old, so your brain is not plastic anymore and you won't absorb language by pure osmosis.
True, I'm not 3 years old, but people who are much older than that can learn another language easier with Rosetta Stone than with other methods. And while it is true that youngsters often tend to learn languages easier than older people, and Rosetta Stone might be rather expensive, I think it's definitely a good place to start.