ORIGINAL: Spidery
I think his pools were generally running low so he redirected the Liberators to help support the ground offensive as that conserves planes and he can use them later on day light raids once he has Thunderbolts able to sweep the bases.
Or he may have decided he doesn't need to destroy the oilfields at Balikpapan and Palembang because he can take them by ground before the end of the year.
Now that he has tried a few night raids against air bases, I think if I started another game I would be inclined to propose a house rule to avoid these - not because of the damage and air-air losses but the massive morale hit even almost ineffective bombing has on groups.
Your experience mirrors mine. Night raids inflicted a steady stream of losses on my planes for only the occasional Allied bomber lost. I'd probably lose three or so planes in the air and twice that on the ground, with an Allied ops loss being the only thing to show for it. Coupled with that, it wrecked the morale of airgroups and in some cases even managed to severely damage the airbase.
My pet theory is that the code for night combat has something wonky going on. I've no proof, and there will be those that will scream that the code is perfect, but it's evident for all to see that something is out of whack with night air combat in general.
I'm a recent convert to playing without house rules, so I'd like to avoid them if possible, even more so considering how HR'ing night bombing is a nerf to Allied capabilities (after all, they have the best bombers), but I do think that something should be done.