To throw more fuel to the flamewar, just look at the Israeli treatment of Gazans...
For a longer essay of the idea of "refugees welcome", from an Iranian refugee who with her parents got asylum in the US after asking many embassies: https://www.theguardian.com/world/2017/apr/04/dina-nayeri-un...
> But what America did was a basic human obligation. It is the obligation of every person born in a safer room to open the door when someone in danger knocks. It is your duty to answer us, even if we don’t give you sugary success stories. Even if we remain a bunch of ordinary Iranians, sometimes bitter or confused. Even if the country gets overcrowded and you have to give up your luxuries, and we set up ugly little lives around the corner, marring your view. If we need a lot of help and local services, if your taxes rise and your street begins to look and feel strange and everything smells like turmeric and tamarind paste, and your favourite shop is replaced by a halal butcher, your schoolyard chatter becoming ching-chongese and phlegmy “kh”s and “gh”s, and even if, after all that, we don’t spend the rest of our days in grateful ecstasy, atoning for our need.
I don't really see it as a justification of mass migration, but I do see it as an argument for treating migrants as human beings not cattle(or worse). There are enough politicians and people in general who think that the boats and people at the borders should be just shot at, that will stop them from coming surely /s. You see this sentiment everywhere, and the "Remember that these are people just like you and I" thought process is missing.