Heroes 5.5 WarGame Edition - Tactical Edition.

Doesn't artillery seem powerful enough as a perk that it doesn't need any additional protective measures?

It's best to judge the power of a skill based on, let's say, real-world testing. What bothers me about it is its inevitability; there doesn't seem to be anything similar at all.
And by the way, I wonder if it's technically possible to split a unit into stacks during the preparation stage of a battle? If so, I think such an option would be a good fit for the Tactics perk.