Something to tickle your brain with: In game development and design, more of X does not exactly equate to "more content". If a crop is added, and its just a different sprite with a different growth cycle, it's not exactly memorable.
Now consider the new rice crop. You can grow this as an irrigated crop, or a non-irrigated crop. The growth cycle is lessened by the irrigation. In addition, you don't have to maintain it. And on top of that, you harvest it and then can throw it into the Mill. This reinforces the use of a Mill as it generates an existing item that's used for cooking: Rice.
Don't get me wrong though, if more of X adds variations to your decision making and how you play the game, then it truly is adding more. Otherwise, less can be more