If I recall correctly we just couldn't come up with a great name for it. To me "expect" is a positive action, but the argument is about it failing to meet the expectation. Semantically I like `thing.unwrap_or(|| panic!("failure message"))`. It feels more like what I would want to say, but it just is so wordy.
Ultimately I'm happy we just picked something and moved on, but still mildly annoys me whenever I write it. If only we found that perfect method name way back when...