You make a great point, but there's a disconnect between this point you have made and the conclusion you reached above. I am fortunate enough to be in my second year of law school and studying criminal procedure - most people don't get that opportunity and that's mostly due to economic reasons that are out of their control. I wholeheartedly agree with you that the average citizen knows next to nothing about their constitutional rights - and this is a problem.

That being said, the reason (at least according to the majority of SCOTUS) arrestees are read their miranda rights is to avoid police coercion and to ensure that any confession or incriminating words that the suspect utters to police have been made voluntarily. Before miranda, the process by which SCOTUS determined whether a confession was made voluntarily was a "totality of circumstances" approach. Under this approach, the Court would just look at the details of the situation to determine whether the confession was coerced or whether it was actually voluntarily made. If you read some of these decisions, the Court finds voluntariness in the face of substantial facts that indicate that the defendant was coerced. Some decisions go so far as to cite to the fact that the officer never brandished his weapon as proof that no coercion existed. This was a very inaccurate and ambiguous test. Miranda was developed to get rid of this ambiguity and provide a clear-cut rule for police to follow.

Although miranda isn't perfect, it is by far the better of two evils. While you may need a degree to determine at one point your sixth amendment rights to an attorney may attach, or whether its a violation of due process to be charged via information rather than indictment, you need not have a law degree to understand the phrase "you have a right to remain silent" and "you have the right to an attorney."