And even if you set aside the moral objections, making somebody tell you what he thinks you want to hear (which has no connection to reality) simply isn’t useful.
That isn't what high level interrogations do. Interrogation is not just a blind fishing expedition by a couple of ignorant boobs, who don't know what they are looking for.
That is why certain military units spend so much training in resisting interrogation, and why so many thousands of federal employees are water-boarded.
According to your reasoning, once someone realizes they can just make up things and don't need to be honest, then professional interrogation is useless.