Some people remark that the aliens have a very stereotypical way of invading Earth. Few people remark that this is just a way to use a stereotype and make their motivation a big surprise, and actually relevant. After all, the souls aren't malignant, just condescending with humans, whom they do not understand. The cultures are also very strange for each other. A case of criticism of ethnocentrism and anthropocentrism?
This troper, having been raised in a communist Vietnam, was struck by the similarities of the resemblance between the Souls' society and the one communism aspires to create - peace and love for all, right down to the Tastes Like Diabetes TV. YMMV, but perhaps this is a subtle way of stating that communism is alien to human nature?
More likely it is because Meyer draws her "inspiration" from older works and the communism-metaphor used to be commonplace in american scifi throughout the era - see Bodysnatchers.
So, Earth is now filled with alien beings who cannot express human emotion. Hmmmm...
Not really. Jeb notes that aside from the Wiping Us Out things, they're just like us (In terms of feelings) when he saw an Elderly Couple together. Wanderer then confirms as much.
Wanderer points out the Soul couple raising a human child as a sign of hope. But what's going to happen when that kid hits the terrible twos and nobody in his world understands human child-rearing, discipline, anger management or even human psychology? How is he going to adapt to a world where everybody he meets is "perfect" and he's not? That kid will be lucky to reach four years old before they put a Soul in him, just to shut him up.