I like explicit over implicit. I will take passing down context (in the sense of the concept, not the specific Go implementation) explicitly everywhere over implicit ("put it somewhere and I'll trust I can [probably, hopefully] get it back later") any day of the week.

I've seen plenty of issues in Java codebases where there was an assumption some item was in the Thread Local storage (e.g. to add some context to a log statement or metric) and it just wasn't there (mostly because code switched to a different thread, sometimes due to a "refactor" where stuff was renamed in one place but not in another).

now your stuff breaks when you pass messages between channels

Goroutines have a tiny stack at the beginning, 4KB iirc. Having a goroutine-local storage will probably open a can of worms there.

Context's spread just like exceptions do, the moment you introduce one it flies up and down all the functions to get where it needs to be. I can't help but think that local storage and operations for Go just like Threads have in Java would be a cleaner solution to the problem.