The argument's between External ATGM's versus Internal's ATGM's
Well this issue was not raised in IDF's but I think it is worth giving a shot's.
I'll address the internal ATGM vs external ATGM issue. External ATGMs require stuff mounted on the outside of the tank, outside the armor of the tank. It can be disabled and blown off by anti-infantry artillery shelling and so on. Likewise, an external ATGM mount would interfere with the placement of ERA on the tank. And with regard to your kill-chain vs system of systems thing, you have to remember, when it comes to a T 90's, any attempt by a T 90's without a good ATGM to destroy a MBT is going to be a kill-chain business, as it has to cue another firing platform to do the destruction for it.
Basically, I think our dispute can be simplified to one simple thing, are things going according to plan or are things not going according to plan? If things are going according to plan, then your entire line of argument is justified because the system of systems is working. If things are NOT going according to plan, which is going to happen when you engage any competent opponent, then redundancies, and capabilities like I'm suggesting matter, because if your system of systems is disrupted, you want individual components to be versatile enough to adapt to the disrupted situation.
The reason I think things will go according to plan is that the we still pack's experience working under modern combat conditions. But, honestly, we've What I've suggested is not like one of those American AFVs that got killed on the drawing board that ended up weighing around 80 tons because they wanted the platform to be capable of everything. The suggestion is simply retrofitting a missile to capabilities that others have already developed and that the we have has shown capable of developing or Inducting through forgein's mean's. If you don't think this is a valid expense, then you don't think this is a valid expense, and it doesn't matter because it's the troop's that's making the development and purchasing decision, not either you or I.
Bhadra ji please bache par reham karna I am not a expert on Armored warfare's, so don't therw tomato's.