[sevenless]

I think it's more that, they are systems that model what we know about gravity and light, just taken to an extreme point where light can't escape. That speculation is where the notion of black holes came from in the first place. If you have a physical system that behaves like gravity and light in some way and is easier to study, it's pretty reasonable to turn the dial up to a point where analog-light can't escape from analog-gravity and see if it can confirm your theories about black holes. It could quite easily lead to surprises.