Programming tools should work this way because we write code; config files are effectively code that doesn't execute (or sometimes does.) A lot of the config files we use (think stuff like: gitignore, eslint/babel configuration, Dockerfiles, package.toml, etc.) we version into source control so that we can track changes over time. I can't think of a good UI that would make editing these files better; VSCode probably has done the best by providing autocompletion in YAML and JSON files using JSONSchema.

Text files aren't perfect, but they're hard to beat. It's not like the hardest part of programming is actually syntax, anyways. You can always improve on this by providing better assisted editing.

If there's anything I'd actually want it would be for software to have pluggable configuration so I can instruct it to pull its configuration from a database or something along those lines.

edit: and on that note, it’s probably the command line interface that actually would strongly benefit from some consideration. CLI arguments are currently a flat unstructured list... but almost everything at least has key value pairs.