Species going extinct doesn't make the world deader.
"Bland" is a better argument. If one bird species spreads across the world and outcompetes 10 regional species, there will be just as many birds as before. There will be less regional variation though.
>Species going extinct doesn't make the world deader.
It depends on why the went extinct. If they went extinct because humans destroyed the habitat, rather than being out competed, then it's unlikely as much life or any life can just move in.
