ORIGINAL: Aurorus
B-29 extended range is 35 hexes. There are many positions from which B-29s can threaten Japan in 1944 and 1945. If the allied player wishes to use vast numbers of transports (and lose many to operations) to keep his B-29 fleet flying at extended range unesorted over targets, rather than using these supplies to refurbish the Chinese army, I am willing to accept that. I would prefer it, in fact, to having the B-29 fleet easily supplied by sea at a place such as Clark Field while transports fly over the hump reinvigorating the Chinese army.
The question is not one of ignoring China. It is one of ¨going all-in¨ on China. It has become an axium that Japan must go ¨all-in in China,¨ and I question the logic of this assumption. A limited Chinese campaign will get some of the ¨low-hanging¨ fruit of extra supply generation in China without using vast quantities of supply in exchange for small, later-game gains in central China.
As you point out, trying to slog through the mountains into China is not a happy path for the allies. It is a grueling slow path with limited supply transport. This tends to support my case that the complete conquest of China and the complete destruction of the Chinese army is not an essential component to every Japanese plan for the war.
I do not see the value of an all-in campaign in China as a training ground for pilots. Fighter pilots will gain experience flying CAP over bases regardless of whether Japan is bombing China daily or not. LBA has limited use outside of China in the later game for Japan... so, in effect, by bombing China, mostly what one accomplishes is to train pilots for more bombing of China.
If Chungking, Changsha, and the other supply generators (including those with free organic daily supply) are left in Allied hands, the transport effort over the Hump is much less important. A 4E campaign could be waged without them, although not an all-out campaign.
You posit using Clark instead. Is regaining Clark easy or cheap for the Allies? Hardly. And it's not an apples to apples question either. If I lose China and have a choice between getting it back for 4E purposes, or retaking Clark, I do the latter. Here we are discussing Japan letting me keep Chungking for free. Easier decision. In fact, if I have Chungking throughout I don't need to wait for 1944 for a 4E party. I can base B-24s there and run rampant over most of China's industry at night. No need for long-range escorts.
The "low-hanging fruit" for Japan's supply is not easy to get either. Look where it is, look at the terrain. Even if Chungking is ignored--and it really can't be if China is to be shut down--the other major industrial cities are a fight for Japan through much of 1942.
But again, if the Allies are gifted China, or just northern China, there's little reason to slog past Lashio. With the resurrection rule and internal supply, plus some transported, China can backstab Japan all by itself in 1944-45. It can't win by itself, but it can bleed them. And the resurrection rule never expires.