There were a number of factors. I need to represent the culture of the age, but also its technology. Firearms were becoming increasingly prominent, accurate and deadly. Swords and breastplates were still important in duels, pikes were still used to fight wars, but soldiers were casting aside all of those trappings for the musket.
But even as they picked up these long arms and trained in them, the culture of battle was rooted in this Roman classicism of mass formations maneuvering on the field. The pace was measured, range tracked, span between each soldier in a line hotly debated. The best strategists were mathematicians.
So, how best to present this all in Moldvay style combat? Making a musket equivalent to a bow didn’t work. The musket has a very different quality to it. I-go-you-go didn’t work. Soldiers often shot each other dead at the same time. Random initiative didn’t work because it caused too much chaos and reduced affairs to luck and bonuses.
While those decisions were rooted in a historial perspective, I also needed to make a clear statement to the modern player. I needed to teach them about how combat was conducted in 1648—or as approximate as I could get it.
Weapon-based initiative—with firearms getting primacy—was the first step, but not the only one. In order to fully form the system, I needed separate target numbers for firearms and melee weapons. I needed set ranges and a variable movement rate (to have those occasional failed charges). Different damage codes. Different skill bonuses. And, most important I think, special critical hit rules.
Weapon-based initiative was the start, but it was just a piece of the puzzle!