Actually, you should avoid expanding appearance, converting fonts to curves, flattening transparency, etc, unless your printer (the people not a device) specifically asks you to.
Those kind of things are hold overs from many years ago. A lot of print shops are still stuck in those days, but the reality is times have changed.
Having said that, we used to ask for expanded gradients, etc because it standardized the files we would receive. We knew what to expect, and what our RIP software could and could not handle. These techniques eliminated a lot of the variables that could show up in production.
On the other hand, we got files that could not easily me modified (for instance, try altering a flattened Illustrator file) and other issues.