Optics, as the OP calls it, is definitely an underestimated problem of modern computing.

So much work goes in most languages into processing nested data structures, especially in this day and age of heterogeneous APIs, and a lot of it is actually not that difficult to generalize conceptually into most languages. A few weeks ago I wrote a PoC in Python and it was remarkably easy to make a lens for traversing data structures.

Declarative optics and updates would make writing business logic a lot easier on so many domains.