What is the most logical reason for the presence of cell walls in plants, fungi, and bacteria? The function of the cell wall is to provide strength and protection from osmotic lysis in all of those cell types, and the cell wall is essential for survival.
Cell walls are essential for the defense of cells against viruses, and there must be variations in their compositions since different viruses infect plants, fungi, and bacteria.
The presence of cell walls is important for the transport of materials into those types of cells, and their chemical composition must have variation to address the different nutritional needs of the cells.
The presence of cell walls is important for cell-to-cell communication, and the different chemical compositions of the cell walls of plant, fungi, and bacteria restricts the intercellular communication to their own species.