I think the writing played to his nastier Kidulthood characterization and Clarke played it accordingly, and because there wasn't much substance to his character, the plot had to revolve around some bullshit military conspiracy around him that made no sense, just to give him more importance.
It still baffles me that after giving us characters like Susan Mendes and Kalendorf, Briggs thought we'd be interested in a selfish, angry cipher like Kade being given top billing over them.
But then I remember the original DE audios were genuine labours of love, whereas DE4 was all about the cheap cash-grab.