Well, Rust has a lot of string flavors, and I like utf-8 being the norm, but there are a bunch of cases where enforcing utf-8 is a nuisance, so getting string features without the aggro enforcement is nice.

There's probably some fruity way to make this a security issue, but I care about ascii printables and not caring about anything else. This is a nice trade off: the technical parts are en-US utf-8, the rest is very liberal.