Oh, mostly inertia. And massive choice.
I've been building VSF forces, but he doesn't have much suitable (though of course Terminators with Assault Cannons = Impervious Suits with Portable Gatlings, etc). As we already play 40k and have been experimenting with Kings of War for fantasy, and also sometimes play Carcassonne and similar games, there is only so much gameyness to go around. Learning a new system always involves a certain hurdle of effort.
But the quick-start guide will help overcome that, maybe.