1) JAL is good for the service but their options are insanely limited. you're looking at arriving Tokyo Station no earlier than 5pm for the NRT flight. and some time around 10pm for the HND flight. for many people it simply would not work (if you also need the flexibility of leaving 6 flights/day).
2) if you need to be in HKG at 1800 and japan the next morning, this and the KIX red eye flight are the only option using oneworld miles. (well there's still the via BKK option)
3) There is a japanese alternative, using ANA.
4) they never use the back for disembarking.