Pretty sure the Imeprial Armour Vraks list isn't rallied against all over the internet because you can take units of Plague Zombies in units of 10-50 because they are OP. They even have strength 4.
Quite frankly I'd be more worried about mobs of 20 Fearless CSM's with I 5 charging you down instead of a few shambling mobs that are very susceptible to pie plates.
It's not like they have poison attacks and regenerate an amount of Plague Zombies equal to the number of models they killed in combat.
NOW THAT would be awesome. I think they really missed doing some cool stuff with the new Chaos Dex and chose a more vanilla approach with, well....everything in it.
Units of 10 slow moving troops are just asking to be farmed for kill points and would be a shining example of more useless rules/troops/models that could otherwise have been fantastic and fun.