I think you’re going a step too far in your description that it “relies” on a compiler bug. The initial measurement of expected benefit was inflated by the compiler bug, but there is still measurable improvement and possibly other benefits to the tail-call interpreter. Also note that this is all called out in an Attention box in the whatsnew note about the tail-call interpreter that was linked in the OP.
As far as the JIT, the team working on it has been upfront about the fact that it is still very early days and so far the focus has been more on retaining correctness and making sure it doesn’t hurt performance rather than making everything faster. There is still a long way to go, but my personal expectation is that when there is confidence that the JIT is generally a significant performance win, it will become an opt-out feature included in --enable-optimizations by default. For now, it’s still labeled “experimental” and strictly opt-in for a reason 
See PEP 744 and associated discussion thread for further details.