Why is it important for meiosis to ensure genetic diversity ?

Without meiosis, each generation would have double the chromosomes of its parents. So it wouldn't even be able to live at all. So for species to survive longer than one generation, meiosis has to ensure that only 23 chromosomes (gametes) are given to the child from each parent. If we reproduced with mitosis, like plants, our kids would have 92 chromosomes.... it would either be hideously deformed or not even born at all.