Lot's of ideas expressed here. Interesting thread. Rant incoming (sorry):
Different people will be comfortable with taking on different levels of topics at their table. Some people don't want to get into any kinda 'grey areas' and just wanna kick down doors and get phat lewtz. Some want to have a lot of moral quandries...the drow army invaded but it is because there land underground was dying and could no longer support life (or whatever). Tastes on all this will vary.
It becomes an issue when one group who enjoys playing one way points to another group who enjoys playing the other way and saying 'I find what you are doing and the way you are playing morally abhorrent.' This is always always always going to start a fight. And no, no, maybe that is not what you are intending to say at all.
But that is what you are saying. Intent, when it comes down to it, really does not matter.
Is portraying a non-human race that does not exist going to cause harm to real people?
It can, but that isn't the default. If someone at your table is uncomfortable with portraying orcs as Always Bad, then as a previous poster said: Be kind. The table might not be right for that player. They shouldn't be made to feel bad because it isn't. I dislike super heavy political campaigns. If I join a table and that is what they are playing, I am not 'dumb' for not liking that group and wanting something different. Nor should I be made to feel so. The people who enjoy playing 'orcs bad' should not be made to feel that what they are doing is some terrible sin.
That said, there is some nuance here. It CAN be done in pretty terrible ways. But 'a bunch of non-humans having a default culture that is evil' is not perpetuating racism in life. It just isn't, much like kids don't go shoot up their school because they played too much call of duty.
It does always amuse me though when people get up in arms about 'orcs bad' but then at the table they spend the whole session killing a bunch of bandits in horrific and painful ways because 'oh they did bad things so of course they deserve to be punished, its okay.'
There was a thread on another forum about how terrible and unjust the wall of faithless was. How it undermined all the good guy gods, etc. These same folks however felt it was perfectly reasonable and just to have Hell or the Abyss torture/eat souls for eternity or whatever though, cause 'those guys DESERVED it.'
Another poster made a very important point and I think it was largely missed: A lot of racist/fascist groups recruit and radicalize people who have been outcast because of not having views that are in the mainstream. So when we refuse to have all dealings with someone who may have an eye rolling view on politics or race, we are not 'being kind'. No, you do not have to play with them. But maybe tell them why, rather than just goodbye, no? Let us all Be Kind. If you are only kind to those you think deserve it, you are not kind. You are just normal. Be kind even to the jerky jerks. World'll be a better place.