G-d gave us free will and many Jews chose to go off. Why wouldn't G-d "allow so many" to integrate? If you really want to speculate about G-d, all these Diaspora Jews who reject the homeland and G-d's miracles by staying back in galut... I would think G-d will facilitate their integration because who needs people unwilling to fulfill their national duties and who choose to separate themselves from the Jewish people and the Jewish tradition?
KWR BT,
As a BT, I am sure you are aware that some personal situations are complicated.
Suppose a man born Jewish grew up in a completely secular family somewhere in Galut. He received absolutely no Jewish education. Quite the opposite, he was taught anti-Jewish ideas both at school and at home. He then married a woman who was a righteous Gentile of Christian background. He married her because he loved her, it did not bother him in the least she was not Jewish, it did not even cross his mind.
Later, around his thirties, without any apparent cause, he spontaneously returns to his Jewish roots and identity. He becomes religious. He becomes a true zionist. None of this is easy. His wife is worried. A lot of people turn their backs on him. He is even hated and called names by some he knew for the change in his life. At best, they think he's gone crazy, they simply cannot understand why he prays or why he spends so much time learning Hebrew or the Talmud or the history of the Jewish people. It's irrational, it's a waste of time, they say. They belittle his spiritual transformation by saying it is a sort of temporary depression and he that he should go and see a shrink who will fix this... Almost everyone around him is hostile to the change in his life and mocks it.
He wants to make aliyah, he knows he should, but he loves his wife and he will not impose such a change upon her just because he returned to Judaism several years after they married. He hopes that, in the course of time, she will accept the idea, but in the meantime he is stuck in Galut.
Would you really describe him as one of these people "who reject the homeland and G-d's miracles" or "unwilling to fulfill their national duties and who choose to separate themselves from the Jewish people and the Jewish tradition" ? Does he deserve this ?
I am not saying this man is representative of all Diaspora Jews who do not make aliyah, of course there are many indifferent and selfish Jews, of course there are many self-hating Jews - but there are many in Israel too, as you know very well...
All I am saying is that some personal circumstances are complicated. The Rambam provides several examples of circumstances in which it is allowed to stay in Galut, but I guess you know that better than me...