This is a fandom related question, so I will understand if people don't get what I'm talking about, but this has been something that's bothered me for a while now. In the Tolkien fandom some races (Hobbits, elves, Men and dwarves) are more playable than others. There is a lot you can do with the characters. You can roleplay their family life, they can go on adventures, Men in particular can be on the side of the Free Peoples, or be Corrupt, or be neither.
The problem arises when it comes to other types of characters, such as orcs, wargs, goblins, trolls and spiders. Although I would like to have these characters in the rp, I am uncertain about how playable they really are. A Men character, even if he/she is a servant of Sauron, would have more freedom of movement to go into the places of the Free Peoples and not get immediately attacked or exiled - they could even 'make friends' or interact with ordinary people so they are 'approachable' by characters that other players have.
From my experience on twitter and other places, orcs, wargs, goblins, etc, don't really seem to last long because players are restricted in how they can play them. A lot of the time, they can only really interact with others of their kind (unless there is a storyline that involves conflict with travelers or some such.) and usually, there aren't any other players with those types of characters to rp with. I don't want a player creating a character like that and then have nothing to do with it.
The other issue is that there are some character types - dragons, balrogs, 'good Maia', 'bad Maia', Valar and Melkor who are very powerful which could be used to make things difficult for people who play ordinary characters by god-moding and such. (The wizards, Gandalf, Radagast and Saruman are 'good Maia' but I don't have any issues with people playing those because they can interact freely and we know that they are restricted in using their powers.)