Let's look at it this way.
Yes, Zombies are pitiful.
but, with a bit of Magical support, you can make your opponents just as bad.
Default spell from Shadows + Any Augment spell = something completely different than Zombies.
Empire Troop: -D3 WS, BS, I, M (Or all of them if you power it)
+ An Augment (Pha's Protection, Speed of Light)
= Something that zombies can stand against.
Empire state troop under the powered effect of the Miasma is crappy. Average of -2 per stat, they'd look like this:
2-1-1-3-3-1-1-1-7
Zombies aren't that far off!
4-1-0-2-2-1-1-1-2
Mmm, hitting simultaneously with Zombies. Not a good day for the Empire.
In the above example, there are several factors to take into account. Which Buff? Did they fail Fear? Is there a Corpse Cart nearby? The Helm? Is it worth it to expend the resources on this unit?
Here's the synopsis for each buff.
Pha's: -1 to Hit. This means they need 5's to hit Zombies. You heard that right, they need -5's-. That should make em survive a round or two, eh? (Also, as a replacement for magic, use the Helm with a Lord. Same effect with the above hex + Augment in play, or you could use both and make it 6's to hit....)
Speed of Light: Zombies now get hit on fives. But, they strike really, really first! This could definitely help them hold a turn or two.
With even half of the equation in effect, you can still tarpit like the good 'Ole days. And if you get multiple buffs, or you buff something even better than zombies (Hah, right?) then the magical side of the battle will really, really help you out.
That was my two cents on how to make Zombies awesome. usable.