an interesting topic!
while we cannot expect our parents not to be protective about us, it is a problem if it veers towards "over-protection". the classic response "It is for your own good" doesnt hold much water since they tend to relate to what they know/experienced when they were of the same age.
over protecting a child would kill any initiative and independence. when they grow up the over-protected children wud be thrown into the very bad world they have been protected from. if parents realise what is good for their kids, it is better if they give them a good measure of independence along with a proper education abt the rights and wrongs (moral values).
kids who have been over-protected and sheltered a lot rarely become good leaders.
as a child grows into adolescence, it is natural to expect some privacy and a sense of rebellion against rules and rulers (read 'parents') parents have to understand this and modify their behaviour accordingly, while at the same time, not giving up control. after all, the final 'Yes' or 'No' is the prerogative of the parent.
while the parents have to give freedom to the kids (esp adolescents), it is important for the kids to remember that
With great freedom, comes great responsibility (with apologies to Warner Bros.). abuse of freedom naturally leads to curtailing of the same and there is no use complaining abt dictatorial parents later.
so, let the child have a private phone conversation, respect the child's privacy over his/her belongings, respect the child's right to make atleast simple decisions, let the child enjoy/sing rap or heavy-metal and nothing wud go wrong. the child wud start respecting the parents in a new way and may not object if the mom or dad (occassionally) try to butt in into a party to have fun (and relive their younger days)
btw, my parenst never over-protected me. my dad's attitude was "let him fall, he will learn not to do that again". i must say i learnt a lot that way.