Except it honestly would - Read the backstory on Mandragoras for example. It literally states they crawled out of a hole after Dalamud's descent. That's so creative and fits them into the lore perfectly! New Races are finicky to add, especially if purely beast like, say Bangaa. The only race that'd largely make sense in current world would be Gria because while Ishgard despises all thing Dragons, when in FF history has it not been seen where unlikely pairings happen? One of the most popular Female Character in FF history is a mix of an Esper and Human.
What this means is, Gria could easily be explained...easily. Viera and such though? They'd have to work some magic to explain why unlike 1.x lore, they suddenly exist.