Battles end too fast because damage can be dealt to easily. Essentially, it currently doesn't matter whether you are throwing in 1, 10 or 100 tanks. Battle is over very soon either way. But that's more a generic issue with deathballs. And it's not entirely caused by the damge/health ratio, but rather by the lack of friendly fire. Which enables basically any unit in play to act like artillery. Sure, rank and file is a legit way to enhance damage, but it's not supposed to scale with several dozens layers of units. Game is supposed to be fast as long as there are only few units in play, after all, there's not (that) much to manage at that time either. But it's not supposed to keep up that speed when the overall number of units increases. At some point in the game, the impact of direct fire units just has to decrease and you are forced to retreat to more expensive units capable of providing fire support. Just upscaling the health only encourages perimeters runs since you are getting even more bang for a fixed amount of metal and you are breaking the established balance of units established by the amount of damage certain units were capable of dealing as "bonus damage" while still out of range of the opposing unit. Tanks are actually hurt most by this due to the fact that their enemies now can just take them head on while they are unable to outperform them by using the superior range in time. Scaling up the number of units while making them obstruct each others more sounds far more sensible and also makes AoE and indirect fire a far more important choice. Other than just abusing the superior range for creeping against fortified positions... (Yes! Mortars can even work with limited range, as long as suitable situations can occur naturally!) Bombers are actually quite a similar issue. The ability to fly through each other AND to fire at the same time just makes them nearly impossible to balance. Forcing them to dodge each other and disallowing them to attack while avoiding collisions would already change their behavior a lot without even touching the numbers.
