Why would anyone want to hand grind their coffee? I often buy pre-roasted beans so that they last longer in storage. This means I have to grind the beans.

I have a cheap spice grinder that does a great job at preparing the beans into ground coffee. It is easy to use, takes 5-15 seconds to process half a dozen cups worth of beans, and I have  good control over how fine a powder to make the beans into. I'm pretty sure this is a similar story for almost everyone with an electric grinder.

I saw a friend using a hand grinder. It took far longer and from what I saw there was no discernable difference between hand ground coffee and machine ground coffee in terms of texture  (if anything the texture was less consistent when hand ground).

Given this, why on earth would anyone want to hand grind?
Hand grinders will work without electricity.  

You can generally get a conical hand grinder cheaper than you can get an electric one.  

They also create less noise than a electric grinder.

Hand grinders will generally produce less heat than an electric (may affect bean flavor).

Many grinders are lighter and smaller than electric ones. They are portable and can easily be packed for use when traveling.

As to the consistency, a conical grinder (electric or manual) will generally create a more consistent grind than a electric blade "grinder".  Electric blade grinders tend to produce dust and boulders.  I know because I use one at work daily and I can see the inconsistency in the grind, but it doesn't bother me that much.  At home, my burr grinder creates a much more consistent grind.