I have suggested before (and received some positive feedback) that grenadiers should also require Nationalism or Military Tradition, so as to push back the advent of Grenadiers and give Muskets longer life on the battlefields.
However, I have built a few musket units, and I have found them, with Combat promotions, to be far more flexible than CR macemen. First, they can kill macemen, and just about any other medieval unit (besides knights, which are still effective against them). Second, the extra strength coupled with Combat promotions is strong anywhere on the map, not just attacking cities.
Their main problem is quick obsolescence to Grenadiers. Should Grenadiers be pushed back a little, and with the new cavalry setup in BtS, I think muskets will be a more attractive unit.
However, I have built a few musket units, and I have found them, with Combat promotions, to be far more flexible than CR macemen. First, they can kill macemen, and just about any other medieval unit (besides knights, which are still effective against them). Second, the extra strength coupled with Combat promotions is strong anywhere on the map, not just attacking cities.
Their main problem is quick obsolescence to Grenadiers. Should Grenadiers be pushed back a little, and with the new cavalry setup in BtS, I think muskets will be a more attractive unit.