> - Why don't git add a native UI? (out of scope)

Git has native UI, just a bad one just like its cli UI, so it is in scope. You've just out-of-scoped better user experience.

> - Why don't excel add lua scripting? (already has visual basic)

Visual Basic is a bad/obscure language. Even real Excel didn't stop and added some JS/Python support. So you've again just rejected better user experience, very nice "project philosophy"!