Should Steam Tanks replace your artillery?

Solution 1:

Cost is as good a reason as any, cheaper range means you can have more/better units in the front line to hold down the opponent forces longer for your artillery to hit them. Alternatively you can use those extra resources on non-artillery ranged units that provides more reliable damage - though I do not favour empire ranged units.

Most artillery also contains more than one cannon per unit. This gets more obvious as the unit size setting increases. Steam tanks however stays as one tank regardless of unit size, only increasing in health.

Solution 2:

Its depend what are you fighting next. If the enemy have artillery, explosive dmg or a lot of range units, you should keep a hellstorm. On the other side if the enemy dont have that and full infantery, its good to have 2-4 tanks.

You should try a combo with full of handgunners, 2-4 tanks, luminark and a light wizard. Also a hellstorm would be good. The enemy just can't get in front of you without dying.