Is it good that private security officers don't have to issue Miranda Rights to a suspect prior to questioning?
Miranda does not just exist to protect individuals. It also protects cops. Miranda allows evidence to be entered in a court of law, and not Mirandizing a suspect can result in valuable confessions being thrown out. If a private security officer detains and questions a suspect, you have entered a gray area. Security officers should not be questioning suspects. They should hold them until police arrive, properly Mirandize, and then question.
Yes it's fine that private security guards are not required to use the Miranda. As larrygates mentioned, security guards may question those they've seen in the act of committing a crime. That right there is an assurance for a suspected criminal--if they aren't seen, it usually isn't an issue. In addition, the suspected criminal is not required to participate in any questioning, and at anytime the security officers can contact law enforcement officials thus ensuring the suspected criminal's Miranda rights will then be followed.
Private Security officers are just that. They are not Officers of the Law, and although they may maintain a person whom they see in the act of committing a crime, they have no more right to arrest a person on suspicion than does the ordinary citizen on the street. If we were to compel Security Officers to give Miranda Warnings, then every citizen who, with the purest of intentions, stops a fleeing felon could easily be held to the same burden. The purpose of Miranda has been narrowly defined by the Courts to prevent overreaching by the government when interrogating one who is detained. Security Guards may not detain one merely on suspicion; but only when they see the criminal act committed. In such an instance, a confession would be hardly necessary or forthcoming.
The answer to this depends to some extent on whose sake we are talking about -- in other words is it good for whom that private security officers don't have to do that?
You could argue that it is good for society and the officers that they do not have to Mirandize suspects. Because they do not have to Mirandize the suspects, the suspects may be more likely to confess. This is helpful to the officers and it helps society by making it easier to determine who is guilty of some crime.
On the other hand, if you are talking about the suspects themselves, it is not such a good thing. The suspects might be pressured into making statements that would incriminate themselves. This is, presumably, not good for them.
Not everything posted here is accurate. In many states, security officers in retail establishments can detain individuals for suspected shoplifting, long enough to conduct an investigation under what are called merchants privilege laws. Also, because now many states require security officers to register or become licensed under state law, they can be seen as acting under the color of state law, thus making any admission of guilt inadmissible because of the denial of the Miranda warning.