What makes this a desirable feature? From the perspective where local reasoning is the most desirable property a language can have, how does homoiconicity support that?

I honestly am curious. I've seen a few examples presented for it, but they always seem like bad software engineering to me. Where's an example that does something in a cleaner way than alternatives present in other languages while remaining compatible with local reasoning?

C has homoiconicity: you can represent C source code as C strings.

I don’t find it appealing when everything looks the same irrespective of purpose and context.