People who become proficient in Rust generally enjoy the syntax, so they want to carry it across. (As someone proficient in Rust who has pondered their ideal scripting language, I would have done the same.)

To your more general question: it depends. AngelScript [0] looks very much like C++, while others, like Lua, don't. It's really up to the designer's discretion.

[0]: https://www.angelcode.com/angelscript/, but https://angelscript.hazelight.se/ has better examples of what it actually looks like in use