This might be a subjective opinion thing. I personally have a very generous and light approach towards Wizards. If they do something that kind of makes sense, then fine. I can always give them the benefit of the doubt. But I also can't stand it when they go straight against logic like with The World Tree.
So to me (and this is just me, I know this) I accept an enchantment creature if it can be explained lore-wise, if it makes a bit sense in the art and if the card text is acceptable as an enchantment. This means it doesn't have to be the best design ever. But a Eidolon of Philosophy is certainly something that could be an enchantment and could be a creature so it's fair as an enchantment creature. Nyxborn Brute not so much. It's not an enchantment by anything except the rules.
So to me (and this is just me, I know this) I accept an enchantment creature if it can be explained lore-wise, if it makes a bit sense in the art and if the card text is acceptable as an enchantment. This means it doesn't have to be the best design ever. But a Eidolon of Philosophy is certainly something that could be an enchantment and could be a creature so it's fair as an enchantment creature. Nyxborn Brute not so much. It's not an enchantment by anything except the rules.