But what if we give first aid tents, only to those heroes who specialize in treatment? It would make sense. And take away from engineering, and give out only ballistas. At the last level of pumping, there can be two ballistas (or two tents) at once.
---
Since it is now possible to choose a hero's specialization when choosing a map, why not give the heroes an advanced specialization (or bonuses) at the start? - They are masters of their craft. A hero with a ranged skill will have a bow with a +1 bonus to ranged combat. A hero with engineering has a ballista from the start. The magician has a book with one powerful spell. A simple warrior hero can have a reinforced army, or a shield and sword (giving +1 to attack and defense) dressed on the hero. You can think of a lot by expanding the number of specializations and the pool of heroes.