Because

The word "because" is not an explanation.  By definition it is a preposition that indicates causation.  It in and of itself is not a cause.

The "explanation" parents use so often: "Because I said so" is not an explanation.  By definition, an explanation details the reasoning behind a decision[1].

The words: "Because I said so and I'm your parent" at least imply the reason that parents are refusing to elaborate is because the parents are in the position of power and don't believe their child/children need to know the reasoning behind a decision.  The ability of parents to believe that their children wouldn't understand or don't need to know astounds me.  The ability of children to ask pointed questions and to comprehend complex ideas astounds me.

The phrase "Trust me" doesn't bother me nearly as much because a) it makes the assumption that the people conversing are equal and b) the phrase implies "If you trust me then you will eventually get to know my reasoning, I just can't tell you right now."

What am I getting with all this rhetoric?  Children deserve explanations.  Real ones.  Not made up reasons because the adult/parent can't be bothered to explain.  I firmly believe that if a child has a firm enough grasp of the issue to be asking questions then they have a firm enough grasp of the issue to deserve an explanation, however rudimentary.

As I child I rarely was told: "Because I say so" mainly because my parents knew I would never accept it as an answer.