And really, when it comes to playability and having fun, does it really matter to them and their gaming group if their idea conforms with someone else's view of what extraterrestrial life should be like, be it science or science fiction? To be honest, no it doesn't. What makes a race "Acceptable" for a given campaign is whether the Referee likes it or not.
At least, that was my opinion on the matter. It's perfectly okay to feel that everything must be scientifically accurate, but I would suggest that such may not be fun or playable to others, and so there's bound to be different opinions on the matter.
In regards to your suggestions about a section discussing non-standard world types, I like it and wish I'd thought of it.
Thanks,
Flynn
At least, that was my opinion on the matter. It's perfectly okay to feel that everything must be scientifically accurate, but I would suggest that such may not be fun or playable to others, and so there's bound to be different opinions on the matter.
In regards to your suggestions about a section discussing non-standard world types, I like it and wish I'd thought of it.

Thanks,
Flynn