There is not only the matter of abuse, but also the constitutional difficulty that this raises if these powers are not adequately framed. You referred to the matter of confidentiality and the role of judges. Judges already order search warrants, and there is a whole regime in place that strikes a balance between the confidentiality required for a police investigation and the need to involve judges for the purposes of obtaining a warrant.
The tools are there. It is up to you to decide whether it is appropriate to involve judges. If you believe it to be appropriate, there will be no problem protecting the confidentiality of police investigations.