The real reason was that Saddam Hussein stood to end up with control, either direct or effective, of most of the Middle Eastern oil supply. 23 years ago, that was a much bigger deal than it would be today.
I suppose one can make the argument that if the US truly was an "Imperialist" power, we should allied even more closely with Saddam, say in return for leaving Israel alone. That would have given US defacto control of all that oil. But Saddam was such an unreliable, despicable sort, that it never would have worked for long.
You are right. Testimony was instrumental in a way to form a public opinion against Saddam, because a few people could buy this war as straight as you described it.
Anyway, Middle East is not any better place right now and I think it made sense to seek leverage and keep Saddam in place.
It could have solved numerous problems, including muzzie terrorist threat.