That is why the game is released in waves, so you go OOOOOH COOOOL and buy the next thing. But 2-3 months later a even cooler squad comes out.
GW can sell lots of minis cause the game has inherit requirements in it, for example in 40K, you have to have at least 2 troop choices in your army and 1 HQ choice. So matter how boring a normal squad of Imperial Guard troopers are, you have to have two choices of them (or two choices of Veterans who are now also troops, but to kit them out you have ot buy several sets to get all the special guns you need).
So if you decide to go normal platoon you have to have a minimum of 2 squads ($25 each) and a HQ ($25) and then you dont have any heavy weapons in that platoon ($18, each) when you can field up to 3. And you only have acces to flamers and grenade launchers in your core troop boxsets, but if you want a melta gun or plasma gun you have to buy yet more.
You can make a vet squad with 1 box of guardsmen, but to kit them out in their special guns and gear you need to buy a HQ set, so its cheaper but barely. And you still dont get a heavy weapon.
So if you would break Dust down into the 40K style of army builds, you would need 1 HQ (Command Squad) and at least 2 troops (Recon grenadiers/rangers and so forth) before you could get into the elites (red devils, heavy grenadiers) or fast (honey, special troops that have higher movement or the fast or agile ability?) or heavy (tank killers, walkers and so forth).
I for one would welcome army books for dust, set up with all the squad stats (not necessarily cards), fluff, examples, strategy and so forth.
But they would probably sell that as a expansion box with two ammo crates, 2 tank traps, a axis hero, a ally hero, a operation (scenario) book and then the army book LOL.