Leaving out "I think" tends to make people think that you are stating a fact that you learned somewhere or somehow, and that it's a step above a "normal opinion

Leaving out "I think" tends to make people think that you are stating a fact that you learned somewhere or somehow, and that it's a step above a "normal opinion"; if that makes any sense. The offense comes in the future as well when they discover you told them something wrong with out the "I think" prefix. Stating opinion as fact is a sure fire way to loose the trust of colleagues.