As you may know/remember, life starts when a sperm cell and an oocyte ‘merge’ together to form an embryo. If their chromosomes where put together into the new child, his (or her!) cells would contain 2 x 2 x 24 chromosomes! That is impossible.
Suppose that the numbers of chromosomes is not halved during meiosis II. Then the daughter cells will each get 2x2x24 chromosomes (total of 96). In the next child, this will become 2x2x2x24 (=192), and in the next ‘generation’ 2x2x2x2x24 (=284), etc etc. This is simply impossible!