With enough practice, you actually can create emotions to an extent, with some being easier than others. Unfortunately, I find the dangerous ones, anger, hate, extreme determination etc. to be easier to create than good one like happiness. I guess it's kind of like the Force in Star Wars. Easier to use the dark side. I'm not sure if it is an advantage or not, but you can also learn to not let any emotion come up, but it then greatly decreases the ability to feel emotions naturally throughout the day.