I'd recomennd doing a web search on the issues they dealt with when they were working to form the Marine Corps Martial Arts Program (MCMAP) around 2000. Significant in this is the timing of it. This discussion and thought was taking place before 9/11 and Iraq and Afghanistan. Of course, while MCMAP and the Modern Army Combatives Programs are thriving and justified and evovled based on war experiences over the last 12 years or so....there is obviously very little disucussion about theory these days as it serves little purpose when you are sending troops downrange daily and cannot afford to take time out to think about developing things through budo like mind, body, spirit on such a grand scale. those things get relegated to the back burner for a number of reasons.
You may be interested to know the MCMAP syllabus includes a heavy emphasis on warrior ethos, character development, and mental discipline. Marine students are required to study about the Marine Raiders, Zulu Warriors, Apaches, and Spartans. In testing, Marines are presented with written tests that include case study identification of past instances in war. The testing requires the Marines to identify leadership values, warrior ethos, Core Values, and martial philosophy in each case study. Some teachers place more emphasis on these values than others, but the requirements are still there at certain levels. This may be dependent upon who you talk to, but from what I understand the primary goal of MCMAP is development of warrior spirit in Marines. This is why most MCMAP tests are prefaced with some extreme form of physical exercises designed to 'wear out' testing candidates, forcing them to push through physical limits and find that 'budo' or 'martial' spirit. Granted there is some potential for hand to hand combat in modern war, particularly with troops embedded with local national forces as trainers, but that does not effect the majority of Marines. I did have a friend use his knife in an altercation while on deployment, but he never identified to me any reverence toward the MCMAP program as helping him in that situation.