Was the Warren Court's decision in Terry v. Ohio a good idea or did it grant the police too many powers and create a precedent dangerous to the 4th Amendment?
I would argue that the Warren Court's decision did not create a precedent that was dangerous to the 4th Amendment.
Chief Justice Warren's rationale for the decision was that the police need to investigate suspicious activity. Activity that might lead to a crime will not necessarily be obvious enough to give probable cause, but such activity still needs to be investigated for the sake of the public's right to safety. When the police (who have a very dangerous job) investigate such activity, they need to be able to ascertain that the person they are contacting will not be able to harm them. Therefore, in Terry, they are given the right to frisk the individual for weapons.
The holding in this case is not dangerous to the 4th Amendment. Instead, it is a valid way to ensure the safety of police officers who are acting in ways that are consistent with the Constitution and with public safety.