I have some code that was doing an @OptIn to ExperimentalCoroutinesApi in order to use channel.isClosedForSend. In coroutines 1.7 that method was "upgraded" from ExperimentalCoroutinesApi to DelicateCoroutinesApi, and now I need to change the @OptIn. Should opting in to Experimental imply opting in to Delicate? Maybe there's a technical reason why it can't work that way easily, but is there also an explicit desire for this behavior?

Experimental is unstable. It could change in semantics, change in binary compatibility, or disappear altogether.