I went through the beta patch notes and there was no mention of it so I will just keep posting I guess.
War Wagons recieves no benefit from Gelt's special skill line, this makes them left behind in comparision to the other units that does. Not only that, but they also don't benefit from the Artillery Tech Tree except 8% missile ressistance. That is just not enough and again, leaves them behind from other units.
War Wagons are better now(After the missile damage buff), but they need to scale with technology. They don't get any reload reduction, missile strength or bonus ammunition. Pistoliers gain insane missile damage and value overall compared to their price and the same with Outriders. War Wagons are left in the dirt. Why go for a Mortar on a Wagon when the regular Mortar can be upgraded with 3/4 of the Tech upgrades and the War Wagon only gains 1/4?
PS: Steam Tanks have the same problem with their Tech Tree. They just get the 8% missile resist. This does nothing to increase their worth where as Cannons increase tremendously in value.