One of the huge advantages, which doesn't really get talked about, of equipping the CFV/IFV with an ATGM is the impact it has on any potential enemy's freedom of action.
Take the CFV for instance, who's primary role is the recon/counter recon battle, providing a screen for the main body etc. If the CFV has no ATGM, an enemy knows that it can't kill a MBT at all, and can't reliably kill other armoured vehicles past about 2000m. So an enemy fighting their own recon/counter recon battle knows they have quite a lot of freedom of action - they can push tanks forward and fight for information, knowing that unless we (Australia) commit our own tanks forward of the main body (which we are not too to do because we have so few) they can accept lots of risk and be very aggressive. Even lesser armoured vehicles can be more aggressive because they know they're not going to be destroyed at 4000m.
Equip the CFV with an ATGM with a 4000m range, and you have given the enemy a significant dilemma. The enemy knows our screen can destroy tanks in a mobile battle, and can destroy his other armoured vehicles at long range, and will therefore be far more cautious and not accept as much risk with his own screen. In effect, we have significantly reduced the enemy's freedom of action and overall effectiveness without even firing a shot. Which, to a large extent, is the essence of manoeuvre.
Equipping the IFV with an ATGM has the same advantage, as it will constrain the enemy's manoeuvre in the same way.