I can’t imagine daily commuting on a single speed bike. The low maintence and simplicity would certainly be nice. But there are days I need to carry a laptop, or extra clothes. I might need to stop at the store on the way home. Or there could be a strong headwind. All of these are reasons to have a nice choice gear ratios on a bike.

I also live live in an area with plenty of hills. I might be less biased if I lived somewhere completely flat.