Well, in most MMORPGs you CAN change your look later … for example in WoW are barbers who let change your face or hair for a small fee. Other games have those features too. … Only the race is fixed in most of the times. I think it would be ok to let the race be fixed, but the face or accessoires like horns or hair may be changed by the use of a crafted tool or oil (for example) … and finaly: PLEASE NO SKINS like in MC … that would be [enter disgusting word of choice] 
I don’t think “skins” are the right answer here either. I really just hope there is enough variety to make the characters come to life. I don’t mind limited choices, if their are many options to choose from. I hope that makes sense. I mean, I don’t need 20 races to pick from as long as the customization feels good. The Pandaren in WoW drive me nuts because they all have the same face. Sure, you can pick a different fur pattern, but the shape and expression is the same.
I don’t want just cat people. I’d rather have a mammal race that let us choose from rabbit, cat, or any other popular choice. The ears and tail would be the big differences. Maybe offer up horns and spikes. The reason I mentioned all the options like I did earlier is I feel like those are things that can be changed from type to type, without making things too odd. I mean, imagine being able to give someone a skin type that you like. Give it feathery skin, but cat ears and a lizard tail.
If the creatures on Oort have enough of their own style, mixing things up like this won’t look so out of place because they are alien anyway.