With such a positive reaction from the Israelites, Moses and Aaron probably felt bolstered with hope as they prepared to meet with the Pharaoh. Their hopes were smashed by Pharaoh's reaction. And the Israelites put into further bondage with the requirement they must gather their own straw for the bricks and yet not reduce their quota of bricks. Why didn't God just rescue them right away? Why did they have to suffer more, first? This is my opinion, so please take it as that, but I think there may be a couple of reasons for the delay and the increasing hardship being allowed. If we skip ahead to Exodus 14, when the Israelites are finally out of Egypt and facing the Red Sea with the Pharaoh's full contingent coming at them from behind, what was their reaction? "We should go back where we were!" "We never should have left!" God knew it was going to take a lot to keep this crowd of people on the move, and if their last memories of working for Pharaoh were the bitterest, that would help. That may have been the Israelite side. But there may be something else as well. In Genesis 15:16, we read that Abraham is not to be given the land yet because "the sin of the Amorites has not yet reached its full measure." In the parable of the wheat and tares (Matthew 13), the tares are allowed to grow to maturity along with the wheat, so the wheat will not be harmed by the pulling out of the tares. There seems to be a consistent pattern (which we see also in the destruction of Sodom and Gomorrah as well as the destruction of the antediluvian world), whereby evil is allowed its full day before it is destroyed. This is scary, but this seems to be God's plan and His way. And so Pharaoh had to be in full rebellion, not just partial rebellion, against God. His evil, which would end up devastating the entire land of Egypt, had to reach full measure -- and then God would destroy him. It may have been a matter of justice in the long run: destruction only after evil showed itself to be what it really was. But, in the meantime, that meant more suffering for the Israelites. For a little while. Perhaps sometimes we find ourselves in the same kind of situation -- just when we think we are about to get out of a nasty situation, everything is suddenly worse. Hang in there. God knows what He is doing!