I wouldn't mind buffing battlewagons a bit and making them more expensive. I agree they're better as heavier units that don't need to be spammed in large quantities to be effective.
I support this. There is problem with swordsmen for sure, they get maybe to much damage from these kind of units (melee except pikes). I don't have experience in balance problems, so I don't know what to suggest in this situation (armor against melee units except pikes if this is possible?).
I thought it would be quite nice to maintain their support centered role, instead of your typical cavalry charge-linebreaker unit. The cavalry of the other factions mostly do the same thing, however the BattleWagon is quite unique thanks to that role. Also, it has fantastic trample, so if you catch a group of archers unaware, they are probably done for.
I think they are fine if you use them as support, in that sense, they could even be cheaper, but then they become quite spammable.
First, you can always play them as support unit, no matter what changes they get in future. Simply upgrade them with supportive upgrades and keep them at side to support units. It is simple and no matter what change they get. Battle wagon was and will be always unique because of its multiple role system, but no one here is discussing about removing supportive upgrades for battle wagon, we are discussing about buffing him a bit and buff its cost which is reasonable. I simply can't imagine heavy machine which is used only for staying in place and heal or buff armor and damage of units. Heavy War Chariots in history (which is some equivalent of battle wagon in game) have always used for mainly one purpose, destroying enemy formation and slaughter of enemies with wheel spikes, not to be supportive unit in general case.
Simply it is out of place to make heavy machine as current battle wagon to be just support unit.
And you can't even use them properly against archers if you are playing against some experience player, because they are always protected with pikes. So mainly you should be able to use them for swordsmen trample and in current game, battle wagons are also weak. Swordsmen deal good amount of damage to them.
Also concerning your suggestion to make them cheaper, I really don't understand why you suggested that. In my opinion it will ruin concept of battle wagon for sure.
Again I must underline it is heavy machine used for offensive purposes, with possibility of supportive usage, not is versa way!
Truly, Dwarves don't break the line, other factions try to break theirs .
That is maybe your experience from other dwarven games, in this game, dwarves are offensive as hell if you know how to play them. There will be always some defensive concept about dwarves (because of their way of living, place where they live etc), but simply if you call your suggestion of making battle wagons cheaper and more as spamming support unit on this defensive concept, I would say it is totally out of place in my opinion, and it will ruin nature of battle wagon for sure.
Regards