Dear Student,
Meiosis is very crucial cell division which reduces the number of chromosome to half. In the case of Megaspore Mother Cell (MMC) , it is a diploid cell ie it contains double the amount of chromosomes. Now for instance, if the cell fails to perform meiosis or meiosis doesn't occur , it will form cells having the same ploidy level ie 2N. Now when these gametes fuse with the microspores (undergone meiosis) , it will result in the formation a whole new organism, which is not viable. Similarly, with the microspore mother cell.
Therefore to ensure the proper sustenance of life and to produce viable offspring reductional division ie, meiosis is necessary and required.
Regards.