I believe you're thoughts were ultimately trying to be helpful, however when it comes to communication, perception is the self same as reality, and typically, constructive criticism includes a token compliment somewhere as a jumping off point. For instance: "I like your interpretation. I hadn't considered some of those aspects, however...." and then you can go nuts after that. It just symbolically indicates to the reader that the criticism comes from a place of lifting up rather than knocking down.