The not-buffering when attached to a terminal also goes back the beginning of time.

I don't see any particular reason for a pipe to be more like a file than a terminal.

And I don't see why my mental model should be file-like and only file-like.

> Trying to make it work with timers feels wrong and would introduce more complexity and deviate from some people's mental model.

Oh, that's the specific proposed fix you meant. Okay, I can see why you'd dislike that, but I would say that forcing line mode doesn't have those downsides.