That’s the same problem I have since long ago.
Musketeer-type unit is a very unique one in the entire AOE series or even among most classical RTS. They are tanky. They have a decent ranged attack. More importantly, they do not have the weakness most ranged units have, which is being countered by high speed units (because they in turn counter most of them). Basically they are the regular heavy melee unit in generic RTS + a range + a bonus against cavalry.
And they also generally have good siege, already making them among the most versatile unit and the backbone of whoever has them. Giving them any more flexibility is going to be straight up broken.
Now let’s count every musketeer unit added since TAD (TWC only has one new musketeer, the tomahawk, which is actually not very good).
Ashigaru: broken (nerfed once, still among the best)
Sepoy: broken (super strong unit in age 2, okay in later game)
Carolean: broken (nerfed multiple times, not so good now)
Regular: maybe the only new musketeer that is okay, considering the cost.
Gascenya: broken (nerfed to probably an acceptable state now)
Maigadi: maybe not overall broken, but that’s 2x musketeer in 1 pop, though quite expensive.
Desert Warrior: broken (now nerfed; though it is an outlaw, it’s still “regular” to African civs, and every civ on African maps used to spam them)
Soldado: can get 2x hp + 2x damage in 2 pop, which effectively makes it >2x musketeer (corrected). And it also has an amazing siege.
Cruzob infantry (maya revolt): 18 range, 5 speed, 1 pop, ranged bonus against cavalry, can be buffed even further. I don’t know what to say.
Now I wonder. Why new civs can get normal hand infantry, normal skirmishers, normal hand cavalry, normal ranged cavalry, but always broken musketeers, which is already the most versatile unit.
I know they can probably be balanced in most games because you don’t always have the time and resource to stack all the upgrades and max out their stats, or you can give the civ a terrible economy. But why should that kind of stats exist in any case?
BTW most of the new musketeers since DE have or can get longer range. I don’t know how that has become the new range standard. Skirmishers or dragoons with variable range are fine, but musketeer is basically a melee unit. If that is the case most civs should get something similar.
Please. If you really have that much creativity about musketeers, give them to natives and mercenaries.