God used the writings of eyewitnesses who He personally instructed over 3.5 years so that there would be just the right amount of evidence for His children to believe but not enough evidence for those who would rather rebel and rule themselves. That's a fine line which offers men two paths - a wide one that leads the many away into darkness and a narrow one that leads a few into light. Jesus said, "Many are called but few are chosen." So we should not expect any alternative solution we can think of that would guarantee that all would believe.
As to whether knowing this in advance will make any difference, I think it will make ALL the difference! Here are a few obvious benefits I can think of. I'm sure there are many more:
If you know about this in advance, you can make other preparations to deal with the fact that you can't legally buy and sell. You can store food, learn to garden, hold crypto currencies or precious metals, team up in self-sufficient communities, etc. (Basically, be a prepper.)
If you do this, you won't be in the tight spot of choosing between faithfulness and death. Therefore, you will be less likely to fall away and lose your salvation.
Knowing this in advance, when the time comes you can point it out to others and perhaps save some of them. Nothing sharpens the mind like seeing prophecy unfold in real time.
Jesus put it this way, "Because of the multiplication of wickedness, the love of most will grow cold. But the one who perseveres to the end will be saved."
This is why the opening lines in the Book of Revelation say this: "Blessed is the one who reads aloud the words of this prophecy, and blessed are those who hear it and take to heart what is written in it, because the time is near."