I have absolutely no idea what kind of jurisprudence Dewey would have brought to the bench, or what the power of the bench might have tempted Dewey to do, but one thing I do believe about what you said in your post is that I have only one objection to any of the "rights of the criminally accused" decisions rendered by the Warren Court: the only one I think they got wrong was Robinson v. California. I do not have any objection to any of the other famous, landmark decisions that the Warren Court rendered on the subject of the accused person's enumerated constitutional rights - not Mapp v. Ohio, Gideon v. Wainwright, Miranda v. Arizona, or Katz v. United States. Decisions like those, and many others, are clearly based on valid interpretations of rights enumerated in the Bill of Rights and appropriately incorporated into the Privileges or Immunities Clause of the Fourteenth Amendment. "Conservatives" who have complained about decisions like Mapp and Miranda have never said one thing that, to me, is persuasive legal argument that the Constitution does not guarantee the rights recognized by the Court in those cases. Richard Nixon and Ronald Reagan campaigned on opposition to the Warren Court's protection of the rights of the accused, but that was merely politicians trying to pander for votes.
Apart from
Robinson, I have to pretty much agree with this. The Warren Court's jurisprudence with respect to the rights of the accused was one of the most profound and important in the history of the country. However, many of the rights that were established or expanded upon during the Warren Court were actually built upon decisions from decades prior. One of the major changes of the Warren Court actually started before it in the 1940s, which was the doctrine of incorporation.
Mapp was the incorporation of 1914's
Weeks v. United States. Similarly,
Gideon was the logical conclusion of 1932's
Powell v. Alabama and 1938's
Johnson v. Zerbst. The Courts that started both of those lines of jurisprudence were quite conservative and were quite resounding in their votes, including the unanimous decision in
Weeks that fully established the exclusionary rule at the federal level.