While I agree that the level of technology and packaging in Japanese robots in generally higher than U.S. counterparts, to take a rather cheap shot, it was U.S. drones and robots that were first on the scene.
Due to the pedigree of mobile robotics, the U.S. needed systems that worked now and not the future...resulting in a variety of heavy duty
operable robots capable of working in difficult environments.
Here's arguably the most advanced robot in the world handling perfectly normal stairs
Conclusion? Make the robot more like a crappy old American robot.
It's critically important PR for the Japanese robotics industry to respond to Fukushima with something of utility. Otherwise these decades of work and millions of Yen in R&D haven't amounted to much more than an interesting series of public demonstrations.
Interesting you mentioned exoskeletons. The US is 5 to 10 years away of getting them on a battlefield. They're commercially available in Japan for medical use. (I'm not making a value judgement on that, except to the extent that "You could actually buy this" is superior to not being able to buy it.)
Actually that's a very good point, and a fascinating demonstration of the differences in commercial funding for a technology vs military funding and the similar but completely different kind of tech that comes out of that.
They had to turn to either a US or French robot to enter the reactor.
If Japan builds robots for the factory and the US builds robots for the battle field, it seem logical that US robots would be more useful in nuclear disaster. An power plant leaking hard radiation after a hydrogen explosion does resemble a battle field more than a factory floor, after all.