You also have to realize things like this have to take scale into consideration. No one is going to do mass manufacturing of battery and electronics enclosures

You also have to realize things like this have to take scale into consideration. No one is going to do mass manufacturing of battery and electronics enclosures with 3D printing, this is a prototyping and hobby level manufacturing system. So the odds of injury and damage are a lot less with this as you automatically self-select down to a tiny fraction of the market share, and only a tiny fraction yet of those will ever experience an explosive outcome from a battery. Also I'm sure that most of this market violates someones IP so again, this ensures that this type of thing (custom making battery enclosures) will never reach a critical mass where worrying about the world burning down due to non-fireretardent plastics is something to be concerned about. But if a person is very concerned about this issue then certainly there are options out there.