>>4653Samus was raised by a race of esoteric space monk bird people, similar in theme to the Protoss. Just as avians. Part of what makes her so awesome is that she was modified to share parts of their biology. Exactly how is unspecific, but we know that her blood is only partially human, and whatever they did made her superhumanly strong, fast, agile, etc, as well as letting her interface her body with their technology, which is where her suit comes from.
All we really know is that she's 'part bird' in some sense or another. Giving her feathers is just a joke based on that fact.