They're also a pain to make. I work on complex simulations for a living, and the number of parameters and data sets you need to get good results is staggering.

They're also a pain to make. I work on complex simulations for a living, and the number of parameters and data sets you need to get good results is staggering. If you end up just going "We think it's about 100 meters" that's a lot of effort for not much reward.