Using your logic...
...we should bomb France simply because it could become a threat to us some time in the distant future. Yup...lets preemptively bomb any and every nation that might become a threat sometime.
Fact is, Iraq was no threat to the United States, or even its neighbors. Saddam Hussein was fully contained, his government was a shambles, and his military infrastructure was completely eviscerated as a result of the first Gulf War and U.N. sanctions.