As Pharaoh's resistance begins weakening he begins making compromise offers to Moshe. Among them he offers Moshe to have the adult men go to worship G-d leaving the women and children behind.
If the plagues are a 'struggle' for sovereignty between G-d and Pharaoh, Pharaoh is now offering a compromise, what might be called Terms of Assimilation. A portion of the Jewish people may dedicate themselves to G-d, namely the adult males, while everyone else will remain as Egyptian property.
To understand this viewpoint it is important to note that for Pharaoh this seemed very reasonable, because the adult males as he saw it, were really the only valuable part of any society. It was the males Pharaoh had ordered killed, not the females. Pagan religions were very often gender specific, men's religious and women's religions. Pharaoh was conceding that this religion was 'important' and could have the adult males.
Moshe's reply was that G-d was not limited to a group of people who chose to participate, but that it was total and it consisted of the entire Jewish people down to their possessions. This is why Moshe would insist on taking the cattle with them and why G-d would command the seemingly selfish and greedy act of requesting items from the Egyptians to take along. The entire Exodus was a demonstration of G-d's total dominion over the most powerful nation of the era in the natural, domestic, biological, religious and economic spheres.
G-d was not and is not optional. A religion that is limited to men is one dominated by men and owned by them, rather than owned by G-d. Pharaoh's view of the worship of G-d and that of some men still today, is one in which the important people belong to. Yet the entire Exodus was a demonstration that people who had been seemingly reduced to the most worthless people on earth, were the ones who would be chosen from among the nations to serve G-d.
Pharaoh overlooked this as the previous Pharaoh had as well, when he enslaved the males but not the women and ordered the killing of male babies but not female. And yet it was women who time and time again thwarted him. First the midwives who refused to kill the children, the women who maintained family life despite the state of slavery, Miriam who watched Moshe's basket and reunited him with his mother, the daughter of Pharaoh who saved him and raised him and Tzipporah who saved Moshe's life on his return to Egypt.
An entire gender whom Pharaoh had overlooked played a key role in thwarting him because Pharaoh could only see value in importance and prominence. And so G-d sent him Moshe as a Prophet, who suffered from a speech defect. And sent him plagues rising from frogs and lice and locusts. All in the cause of redeeming a people Pharaoh thought worthless slaves. Rather than learning any lesson from this about falsely presuming on what is despised and worthless, Pharaoh continued attempting to treat with G-d on those former terms. And when all was done all that Pharaoh had continued worthwhile was taken from him, from his first born son, to his army and the prosperity of his nation; all because he had regarded a people as worthless.