Respect to the cadaver was teached in our first dissection class and not even once any incident like that happened. On the other hand, I've seen a lot of disrespect coming from veterinary students, which brought me some disgust.
I think this is a special case of emotional transference.
I don’t personally see a reason to treat cadavers any differently than any other object in a lab. They’re not people. Do we need to be careful to show respect for our mobile phones? How about our coffee mugs?
Even from a purely consequentialist point of view: if behavior around the cadavers gets out to the public, and the public deems it disrespectful, the public stops donating cadavers, which negatively impacts medical education. Even if you don't personally believe in treating human remains with respect, a huge part of society does, and you have to at least respect that.