Why are battery-powered lights so popular? Both on this site and "in real life", battery-powered lights appear to be at least as popular as generator-powered lights.

I have always been slightly confused by this. To me, a generator-powered light seems the better solution if you need light regularly, because there's no need to worry about charging, and because they can be permanently attached. Yet many people seem to not only prefer battery-powered lights, they appear to not even consider a generator.

Why is that so? What are the advantages to battery-powered lights?
The main advantage, in my view, is that you can more easily add/remove battery-powered lights.

Why this may be desirable:


Theft resilience. I take my lights off the bike and carry them with me if I'm parking my bike outdoors for longer than a few minutes. Caveats: This can be more of a downside than a benefit, depending on your situation. (I can't imagine a thief taking the time to steal a generator-powered light, but I'm sure it happens sometimes.)
Flexibility. I don't bother to take my lights with me unless I know I'm possibly going to need them. If I used a generator-powered light, I would be pretty much stuck with it all the time, even if I'm only going to ride during the day. Caveats: This is, however, not much of a positive thing, unless the lights you use are particularly heavy, or you happen to be a "weight weenie".
Interchangeability. I can swap my lights between my bikes very easily. Most decent battery-powered lights have an adjustable removable clamp that you can use to attach the light to any style of handlebar/seat post/other tube that you could possibly want. This means that I only need one set of lights that I can use between all of my bikes. Caveats: If you don't like to spend an extra 5 minutes swapping your lights every time you want to ride a different bike, this is not a plus.