Human cadavers are VERY hard to get. The paper work on a single donated human body is a good half inch stack and all are kept behind locked doors. Thus animal models are used as a first line of study. Many students who think they want to be a vet, doctor, or nurse get out of the field after using an animal model. I've gone though things from a worm to a human cadaver and when you compare anatomy, it is amazing how much we share with other mammals, even mice.
The key is for students to show respect to the specimen they are investigating, be it a mouse or a human. Just because a cat is a "pet" a chicken is "food", and rat's are pests which people set poison out to kill, why should they not be respected the same? If a student is taking the experience for granted, it may not be their subject and that is fine, open up that space for someone who wants the experience.