So not quite as benign as BoxCrayonTales put it.
Volo literally describes orcs, sapient beings, as being "domesticated." I shouldn't have to explain why that sounds disturbing.
Yes, orcs, gnolls, trolls, blah blah don't exist and don't represent any particular real group of people. The whole concept of evil races of sapient beings with cultures and families and blah blah blah inherently displays parallels with the racist propaganda used by all human groups throughout history. You dehumanize your targets so that you don't feel guilty for killing them and their families. The same rhetoric was used to justify genocide by colonizers.
The game world is contrived so that humanoids really are subhuman scum you can mass murder and "domesticate" with impunity, rather than people being brutally exterminated by sociopathic "adventurers."
There's nothing wrong with playing violent genocide fantasies. Cowboys & Indians is a children's game about genocide and nobody denies that it's fun as heck. We shouldn't pretend that they're not violent genocide fantasies, though.
For that reason, I advocate playing Violence: The Role-Playing Game of Egregious and Repulsive Bloodshed.
http://www.costik.com/Violence%20RPG1.pdf