There has been lot discussion in Finnish army of why CV90 doesn't have missile like German marder, bmp serie or Bradley.
In conclusion it comes to something like this.
CV90 is not meant to operate agaisn't tanks. It works with them but not agaisn't them. It is supposed to cover tanks and infantry from other infantry and light vehicles.
As for tanks, or tank combat treat, CV is supposed to carry troops close enough to ambush tanks, and to provide cover and fast retreat for infantry that ambushes tanks with rpg.s or missiles. unlike in steelbeast AT teams actually move really hasty. At least in Finnish army. (Im trained to Heavy basookas there so I know.)
As I see it. Infantry takes out tanks with missiles or basookas, and CV90 moves in to take out rest of the treat while infantry retreats or finds new position to attack.
As addition reasons. CV90 doesn't have missile system since it is slow to deploy and would lead CV90 to be potentially in danger. It is more safe to dismount troops to engage possible treat. Also by this way. Infantry would not be in danger to share hit if cv90 is hit.
As I see it. It is all about tactics. Players probably want to have ability to engage tanks while in vehicle. But at same time take their vehicle in greater danger than in case if they would use infantry to do so. But as well they would likely want to use vehicle rather than infantry since infantry in steelbeast sucks! Beside that I think with right tactics CV90 can still be more than just battle taxi that it seems to be at the moment in steelbeast.
Another thing I hear frequently is that for example bradley or bmp is not NBC protected while loading missiles. Likely cv90 would not be. So that is one more argument why not to have missile. Although well.. one argument there another here. Pros and cons.
Currently in the game CV90 works as good scout vehicle, and "decent" anti air. Too bad that not many know how to operate CV:s anti air modes.
And for those who hunger CV90 to have ATGM... it has variation for that. Just no one purchased it so far that I know.