It's not like the undesirable slot times at HND were a surprise - airlines knew about them and specified in their applications when they proposed to land and takeoff at HND.
AA was blindsided at PEK as the initial slot times were a complete surprise and a departure from typical Asian flight arrival and departure times.
As WT has indicated in the past, HND is not yet ideal for connections (other than intra-Japan flights) - if you can't make it work on Tokyo or Japan O&D, better to step aside and let someone else use the scarce assets.
The place for connections is on the USA side to fill the plane mainly with people who want to go to Tokyo, not the crowd that wants to connect to SIN, HKG, ICN, BKK and mainland China. For now, NRT flights are the better place for non-Tokyo bound traffic.