In those few, extremely rare cases are enough to fuck up a nation's politics, immigration isn't the problem.
They're rare, but not impossible, esspecially when it comes to the involvement of powerful/rich governments, corporations or individuals. We already have enough of that, no reason to make it easier for effectively no gain.
Edit: esspecially considering that ability to chose the location your child is born in is based primarily off wealth rather than moral character or anything else positive.
So we give up with a half-measure, that helps the rich moreso than the poor without addressing the underlying issue?
This isn't a helpful or sustainable approach. Should we give up on climate change because reducing carbon output is hard, or say, "Well, as long as you don't use coal, its good enough." Of course not. Not to mention that making immigration and/or citizenship more accessible isn't an impossible task at all, esspecially relative to climate change or weath inequality.