I agree with SEagle on several points that he mentions...
Depth perception, do you think the Iranian Navy has it?
That is a true statement and that is why the schmiran wasn't a big concern to the brass. They were more concerned about its impact on large surface vessels from a fast moving surface contact. Less concerned with the hypothetical threat to only submarines that you describe in your post. Once launched the torpedo has very limited guidance on a horizontal plane and much less vertically. For most Navies (except one) the tech isn't there yet.
I agree and disagree, there are subs that work with battlegroups and subs that don't. Plain and simple for all the reasons that you mention. I wouldn't want to command a sub attached to a battlegroup, who would? Subs on patrol are rarely continuously attached to a battlegroup unless considered necessary. They are alternated during patrols to cover the battlegroups movements.
Crater
