If God loves us so much, why doesn't he let us come to heaven and not have to stay on earth?
God created a perfect spot for mankind to be, and then mankind blew it and didn't obey His command. So we got plan B. The thing is, God always goes through with His plans - so plan B it is.
At some point, plan B calls for Christ's return in the air to gather the people who have accepted Christ as Savior to Him, but the timing is up to God. The early church expected it to be soon. But during their lifetime, Israel wasn't its own nation - it was part of the Roman empire. Now that it's a nation, plan B could enter into the final phases at any time. That's a short answer for why plan B in the collective didn't have a chance of happening till a few decades ago.
If you're talking individually, remember that the Holy Spirit is there to help you through whatever bad times you may be having. God has a purpose in each person's life and He wants us to fulfill that purpose. He could take us to heaven at any time but everyone who dies is missed by someone. Sometimes it is hard to stay when the suffering is large - and many Christians suffer more than the American Christians even think of. It's easy to want to be taken to something better where there won't be any more hunger, or pain, or temptation, or any of the hundreds of thing that buffet us day by day.
But plan B has its own timetable that isn't for us to know the specific details of. It's just up to us to get ready and stay ready.