Yes, but it depends on the "type" of nurse in question. Regular nurses work under the direction of a doctor. However, there are also nurse practitioners, and they can and do make medical decisions for patients. In this litigious culture, giving somebody the wrong medication can and does lead to lawsuits.
I don't see why you nurses shouldn't get malpractice insurance. Unless you're a qualified nurse or know a lot about the medical field I wouldn't be passing judgement. The medical field itself is chalked full of risks since people are supposed to "trust" you with their lives. Doctors, surgeons, and a lot of other medical specialists can get insurance. Hell, you can pretty much insure almost anything that you can think of that could go wrong. Saying that nurses shouldn't be making their own decisions blah blah blah and screw up the patient somehow is a load of bull. That's like saying you drive an automobile and you don't get insurance because you passed the driving test and therefore you should know how to drive. But you get insurance just in case.. even if nothing goes wrong...am I right?
If nurses are going off on their own and making their own decisions regarding a patient then it's going to end up going poorly for them one way or another. If they're following instructions and generally being an extension of the doctor they're working under then they don't need this, they're just applying what their superior instructed them to.
Nurses are working at the direction of another person, whether it is the doctor, nurse practitioner or the hospital itself. Any mistakes made by the nurse should be covered by the malpractice insurance of the entity making the order. If nurses were required it would just open up another avenue for plaintiff's lawyers to generate revenue, it would not protect patients, nurses or doctors any better than the system no in place.