We're well on our way to having "secondary" versions of many base game species, and greater flamingos really aren't all that common in the US, at least. American flamingos are much more vibrant, and both they and Chilean flamingos would help flesh out the South American roster. That's not to say that an ibis or spoonbill wouldn't also fill those roles, and in a perfect world I'd like to see all three, but it makes sense to me why people would want a second flamingo at this point. It also feels arguably a bit more realistic given Frontier's apparent hesitation to roll out truly unique birds.And the scarlet ibis.
I don't understand this obsession with the american flamingo that is getting so much track lately. I prefer a unique bird model/rig that we don't already have like an ibis or spoonbill than a flamingo reskin. The american flamingo is great for an anniversary animal.