Based on this prompt, I believe that your answer needs to pick a side of the argument. This might be tough. Modernization is a double-edged sword. It has many advantages, but it also has many disadvantages; however, teachers generally give students an either/or prompt to see if you can take a position on an issue and defend it with evidence. "Sitting on the fence" is not generally well received by teachers.
Modernization is usually associated with urban and industrial development, and your definition of its increasing the amount of specialization and differentiation of structure does apply. In modern society, people tend to be specialists in very specific areas rather than generalists. This generally increases production rates while increasing the quality of products being produced. Increasing quality while lowering prices is a huge benefit to the general population of modernized societies.
A disadvantage of modernization is the environmental impact that it has on the planet. A modernizing society (or fully modernized society) demands a lot of natural resources in order to build buildings, operate factories, and sustain the population. These heavy usages of resources lead to increases in pollution of both water and air. There is sufficient evidence that global modernization is a main contributing factor to climate change. On the other hand, the demand for those resources from modernized societies can help elevate poor countries that happen to be rich in those resources.