In Japanese the plural is very specific. When you pluralize a noun, you need to specify exactly how many of that noun there are.
The idea of adding an "s" to the end of a noun to change it from referring to 1 object to 2 objects isn't so difficult. But the idea of using the plural to refer to a class of things (Do you like dogs?, for example) doesn't exist in Japanese. In Japanese, the singular is used to refer both to specific objects and to classes of objects. The plural is only used to identify a specific number of any given object.