Trick
Auror
The number of things in a fantasy work that depart far from reality are too numerable to list, but this is the one that does it for you? I don't think it is any more unrealistic than having dragons flying around or wizards flinging fireballs, or gods intervening in mortal affairs, and so on.
Actually, yes, and ideas like it. I love fantasy but there are many instances of ideas that lack explanation and I prefer something more definitive. If you say, "In this world, magic exists." I can take that at face value but saying, "All Orcs are evil." and then just moving on, especially in an epic work, doesn't do it for me. I'll even qualify per Mythopoet's assumption: "All Orcs that appear in this work are evil, and I will not discuss any other Orcs who may or may not be evil." That doesn't work for me either. This is just my taste, not the way things should be definitively. I want more conflict based on real emotion, from villains especially; even nameless villains without speaking roles are people.
One could argue that the Orcs are closer to animals than men. I don't agree, but even if that were the case, have you ever met an evil dog? A bad dog, sure, but that's because of bad owners. How about an evil puppy? Probably not. Since I can't see Orc babies trying to kill as soon as they can crawl, it doesn't work for me. I just want better backstory/explanation.