In cell division, there are three main functions. Growth, repair, and reproduction. (Think of it like GRR). Growth is the function that allows organisms to grow bigger. People cannot grow on their own without their cells dividing. When you're a baby you are born with a certain amount of cells, but as you get older these cells divide. This process creates more cells, which then causes you to grow. When these cells are dividing, they are reproducing. Reproduction all starts when two parent cells combine and form a new cell which undergoes cell division. So cell reproduction is really how your body grows. The last main function, repairing, is also very important because it is the function that replaces damaged or aging cells with new healthy ones. So now you know why cell division is actually a very important process and if it didn't occur then humans wouldn't be able to grow and wouldn't live very long without the replacing and repairing of damaged or aging cells.
The picture above shows a Blue Hyacinth plant growing through cell reproduction.