Honest question. Is metaprogramming really that beneficial for any application development? I can certainly see the appeal, but how much will it improve productivity or quality compared to shipping features without it?

Isn't the actual wrong turn focusing on a metaproblem rather than the problem you set out to solve?

Metaprogramming is just macros: code that generates code. One use is to get rid of repetitive code patterns. Another is to move certain computations to compile time. Your statement that metaprogramming is used to solve a metaproblem is just wrong. Those two words are only related in that they share a prefix.

I get what and why of metaprogramming. I was specifically trying to quantify working without it. My reference to metaproblem wasn't what metaprogramming you want to do but rather solving the problem of a lack of it by switching languages mid-development.

How often has a commercial project been rewritten to gain metaprogramming mid-dev? I added commercial because personal projects have different objectives.

Third is to introduce new concepts into your language as if they were part of that language from the get-go. Which can entail both eliminating repetitive code patterns and doing computation at compile time.