I'd argue that the in-browser Flash Lite experience I've seen on Japanese phones is incapable of doing very much well, let alone an interactive webapp, though I'd imagine in some cases it could get by.
Ironically Japan is probably one of the only places in the world where the 3G networks are fast and reliable enough to actually make AJAX halfway feasible on mobile, and DoCoMo have the muscle to push a single standard implementation to remove the large cross-browser fragmentation issues, but with standardised well-integrated DoJa support offering a richer experience maybe DoCoMo don't feel the need?
I'd completely disagree with the idea that AJAX is a tool of choice for any developer who wants to develop something for a normal user on a phone though (can you name any successful deployments where this is the case?), even though you're right in suggesting a task-oriented focus for users. For the forseeable future mobile AJAX will be stuck targetting the minority niche of users who actually own a new S60/iPhone handset and live next to a 3G aerial/WiFi hotspot with flat rate/free data tariffs.
The Japanese are just going to have to accept that they are stuck in mobile purgatory with the most used mobile services in the world and superior mobile functionality to the rest of the world, but without the manifest benefits of full buzzword compliance.