We know that the undead is suffering from massive tanks. However, I think the fundamental issue is that siege vehicles in War 3 do not play the role as intended.
Meat wagons are the worst siege vehicles is an issue for sure. but a lot of other issues come from it.
- They are too uncommon to the point of being useless.
- Too many tower rushes. Due to underpowered siege vehicles, tower rush is very common in War3 and very hard to defend for new players. They just quit the game.
- Siege vehicles should not damage friend units.
- They are too easy to die. Too little HP and armor type is not Fortified. Movement speed is also probably too slow.
- Many heroes and units become useless due to underpowered siege vehicles. One very obvious example is the meat wagon. Necromancer is clearly too useless because of the underpowered meat wagons, despite in Warcraft lore, massive undead skeletons are summoned are how undead works. Another example is the Priestess of the Moon which is a very pointless hero. A rework on siege vehicles would significantly help the situation here for those units that would play around siege vehicles.
- Attack range probably needs a further buff so it should be difficult for enemy players to ignore them.