Simplicity extends to practicality, especially in foul weather. Back in the day my friends and I used to ride fixed during the winter to save our road bikes. It's also good for off-season spinning to keep the legs in shape. Single speed has many of the same benefits, while allowing you to coast. That's either a good or bad thing, depending on your pov.

I live where it's flat, and although most of my bikes are geared, it wouldn't be that hard to ride FG or SS exclusively. In TN it doesn't seem like such a great choice, unless it's just for short errands on relatively flat ground. If this is your main bike or your only one, I'd strongly advise against it.