The idea of introducing arquebusiers for the Spanish has been discussed in some topics because it is their most important main unit and apart from that it already exists in the game (the Chinese have it).
But since it is difficult for developers to introduce it only for Spanish people, I had another idea.
What do you think if they introduce it for European and Asian civilizations?
In the first place, one more unit leads to counters, strategies, dynamics. And for example, in the case of the Spanish, they would be viable in the early game and with unique improvements.
Secondly, he could be even with the musketeer but with opposite stats;
-Less range but more damage
-Less melee damage but more siege (like the Ottoman howitzer).
-That it costs the same or different resources.
-Or why not? that is like a more expensive and stronger crossbowman.
And thirdly, it would give a fresh air to ancient civilizations that are a bit forgotten.
According to the story it should be an early game unit that could not do anything against the skirmisher but why not, counter the musk on various occasions or combine them with them.
I await your opinion
(sorry for my bad written english)