Hi, from my point of view using MIDI for software-controlled dynamic music in modern games is a very interesting and promising path, truly next generation.
The advantage of this approach is exactly e.g. music changing "mood" based on the situation in the game. A small implementation is showed in other our video, here
But I think, that this application is definitely not the end of the benefits (apart from, of course, typical technical advantages related to the size of the files and the database of ready-made songs). I would be interested in the opinions of experts in MIDI technology.