Here we are again!
Paul in I Corinthians 7 is dealing with a very particular and hard situation for the people in that congregation. It was a "present distress" (verse 26) that led to some of what he said.
Paul actually taught that the end of the world WASN'T night to them at that time (II Thessalonians 2:1-3, but especially 2). The other prophesies were regarding specific events in that time. The statement about women who were pregnant was made by Jesus regarding the imminent destruction of Jerusalem that happened in 70AD, not the end of the world (why would it matter if you were pregnant if God is taking you out of this world?).
I do see the point that you are trying to make here, but I think you're missing a portion of what Paul is saying.
The drive for sex is a natural one to mankind. It is ingrained into us. Every single person has it.
However, the Bible makes it clear that sex should be reserved for those within marriage.
The point of what Paul is saying is that many people fall into sin by giving into that drive, and that doesn't just apply to Christians. However, if you are married, you're not sinning, since you are getting your sexual outlet in the way that you should.
Sure, there are some people that control themselves and don't have sex. But those people are an exception to the rule of human existence (whether Christian or not). So, this isn't talking about some weakness particularly for Christians, but a message to Christians about how you can properly have the outlet for the temptation that everyone has.
I would also point out that using the WHOLE Bible, and not just a single passage, marriage is a blessed and supported institution under normal circumstances.
I think what you're asking really comes down to a misunderstanding of what Christians are saying.
Sure, there are a few fools out there that think they can guarantee the end of the world will happen any day now, but that's not something that they can prove in any way. Christians have thought the end was nigh for a long long time (or else why would Paul take the time to tell the Christians in Thessalonica that it wasn't imminent for them). Just ignore the people that make such claims, since they are an embarassment to the rest of us.
What Christians are saying is that we should live every day as if it was our last. That could be either Christ returning or us dying.
That doesn't mean we should quit our jobs and spend the entire time in prayer. That means we should be living in a way that pleases God by what we do.
Does that mean we shouldn't get married? Marriage is a gift from God to make life more enjoyable and to be able to build another person up in a way that can't happen without that close personal relationship. There would be nothing wrong or harmful in pursuing such a relationship.
Should we not then have children? Children are also a gift from God and it is a priviledge to teach them and help them grow. There's not a single negative or harmful thing about pursuing that.
At the same time, since there is no guarantee that today is that last day for you or me, we have the responsibility to carry on with life as normal. That means doing our normal things and attempting to live a life pleasing to God. Part of that is getting married and having kids.
I Corinthians 7 isn't about the end of the world, it's about a specific series of events happening in the city of Corinth in those days. There was severe hardship and persecution. Because of that, it was easier for single and childless people to be able to survive and serve God, since they would have no one else to be concerned about protecting.
That same passage doesn't apply to a possible "end of the world."