I do have two points I'd like to push back on, though.
1) It seems that the U.S. Army's lack of foreign language competence (the example you shared of Korea comes to mind) is not necessarily evidence that such competence is nearly impossible to achieve. Rather, it could also show that language competence is an underappreciated aspect of Soldier and Officer education, as Admiral Stavridis, GEN McChrystal, and GEN Odierno have variously asserted.
2) Comparing the broadening experience of a language major to that of an engineering major w/the core language courses is as difficult as comparing apples to oranges. The language major, if he applies himself, can gain and maintain competence in navigating another nation's linguistic and cultural differences in order to build strong human relationships. The engineer knows how forces and materials interact in nature and can accordingly harness them to build (or destroy) strong structures. Both can prove immensely useful, depending on the problem at hand, and both have had their thought processes expanded by their studies.
Apologies if I am reading anything into your post that was not there.