JL would provide a ton of connecting possibilities for DL in Asia. With NW's NRT hub in the fold, DL wants more connections there in additional what it serves with its own mental (still NW at the moment, I guess). Risky investment during this economic climate, but probably a boon when the economy rebounds.
LAX
True, but they could get those connections through code shares. Buying a loss making carrier means that you as the purchaser think that you can do a better job running the show and have lots of synergies. And running a Japanese airline will be a challenge for anyone but especially for any
gaijin.