exalt,
You ask why? The MCF joint venture started in 1992 over 23+ years now. Obviously, they are making money as MCFA in the US has undergone several facility expansions during this period. So everybody Cat & MHI are both happy and Jungheinrich too.

How the buyout Nissan/TCM plays out is yet to be seen-but have confidence that MHI/Nichiyu do have a plan that will unfold over time. One of the chief guiding principles of Japanese companies is they operate under the principle of a continuing Plan-See-Do process.

So it would be best to just sit back and relax to see how the rest of the story unfolds vs playing an armchair quarterback - as in the American version of "football"

Another thing that one needs to understand Mitsubishi (MHI) & Caterpillar Inc. have had an even much longer relationship (starting in the late 1940's - I believe) in the construction equipment business side - MHI used to build excavators, small bulldozers & motor graders for Cat as well as selling small HP diesel engines to Cat under a private label agreement. In the mid/late 1980 MHI sold their excavator operation in Japan to Caterpillar Inc. Can't really comment on what the current relationship is between MHI & Cat but they have been " strange bed fellows" for a long time.
Here is an article from 2008 you might want to read http://www.prnewswire.com/news-releases/caterpillar-mitsubishi-heavy-industries-and-shin-caterpillar-mitsubishi-announce-definitive-agreement-for-japanese-joint-venture-57124787.htm