I think at some point you have to ask is the Federation going to save every humanoid species that is in danger and relocate them to new homes? That would take massive manpower, we are talking about billions of people per planet. Who gets to choose who lives and who dies? How many starships would be required for this? Would the Federation only be saving those in Federation space? What about their own territory, are they just suppose to ignore their own homes?
I think the whole thing becomes too big.
If they are capable of FTL, they can save themselves. The Federation wouldn't have any issues helping them through the process.
As far as we know the Q Continuum are omnipotent, but you don't see them going around saving cultures.