I used to ride a singlespeed due to derailleur frustration until I learned the frustration was not due to the derailleur but due to the indexed shifters. I believe the reason we saw a resurgence in singlespeed bicycles was due to the advent of indexed shifting, which can be so frustrating to deal with that you just wan't to tear it all off so you can ride.
I think derailleur gears are amazingly awesome, and I love super low gears (my lowest right now is 22x34 on one of my bikes) for when I am loaded up. Nothing better than just effortlessly spinning up a hill. Friction shifters simplify the whole process and make interchangebility much greater. Set the high and the low and your done. No finicky adjustments required. The derailleur is one of the greatest invention within cycling. But index shifters not!