I think comparing it to a tank is a false equivalence given that this is Japan. It would more likely be designed for non-military purposes such as search & rescue in the aftermath of a disaster or other humanitarian crisis. Though, again, military or civilian, most tasks which would justify the price tag can be accomplished better and cheaper by unmanned systems.
Here's the problem with mechsuits: For the cost involved, you are better off investing in a fully-mechanical system operated by remote control with AI assistance or near complete AI control. It minimizes the risk to humans, as these systems are far from invincible, while simultaneously cutting costs as it does not have to fit a person inside or protect said person.
What do you mean by fully mechanical system? A bipedal robot? I would think the costs for that would be far more than exoskeletons.
The purpose seems more for adding strength to ground troops. Troops that you cannot replace just because you have tanks and planes. We will always need a human involved right in the action simply because there are no robots for the foreseeable future that have the versatility of a human.
By unmanned system I do not mean 'a robot that looks like a man,' I mean 'a robot which was actually designed to do the task.' Or more likely, a large number of smaller robots. $750k can buy a lot of those. For recon within broken terrain, small robots capable of fitting through tight spaces and such will be king; for recon within intact terrain, flying robots like
DARPA's hummingbird would be more effective. For carrying large loads over distances, something akin to
Boston Dynamic's Big Dog would be more effective
(and the US military plans to use the LS3 successor to it). Lifting materials is a bit more tricky simply because of the range of materials/weights, but again, can be done for much less than $750k/unit. Adaptive swarm robotic systems for moving materials are pretty much at the same point in research as exoskeleton systems; be it ground based or
similar to quadrotors.Similarly, I think you vastly overestimate the difficulty of AI systems for relatively narrow (as compared with deep problems like a strong AI, which are in fact very hard) problems like those associated with such tasks. Keep in mind, the modern approach to AI has been around for only a couple decades thus far; and it's already at the point where it's driving cars autonomously; a problem which is arguably as complex as those any of the aforementioned robots would be involved in. Especially since they would be probably only semi-autonomous, with high-level tasks planned by operators who are in the safety of somewhere which isn't a warzone or disaster area.