Well, if you could fire a Klub missile from 100 km let’s say, or at the max range of the 650mm which is even smaller, you reduce the reaction time of the escorts and you could have the missile go faster as it won’t need so much fuel + the supersonic dart covers the last 20 or 40 km. I think this is much more effective than the 650mm torpedo launched at the edge of the envelope and the carrier has less reaction time (running away, escorts launching 324mm torps), nor the ability to sacrifice a frigate or two in order to stop the torpedo if all else fails (the Klub will likely be able to differentiate the carrier from the other ships easily).
Also, the Yasen is even larger than the 971, you probably won’t use such a sub to deliver swimmers and risk it close to the shore. It is more or less a golden fish right now.

1) Klub-S can be fired from normal 533mm topedo tubes, so why bother with 650mm.

2) Perhaps a big sub shouldn’t be used to deliver swimmers to shore but 650mm tubes allow the use of large tubelaunched swimmer delivery vehicles, allowing the sub to stand-off much farther than a normal sub (though perhaps not as far a an USN Los Angelos class attack sub with Advanced Seal Delivery vehicle on its back … that SSN not exactly being small).

3) Not all underwater vehicles are necessarily (or even primarily) for swimmer delivery. Think ‘unmanned undersea vehicle” or even ‘autonomous undersea vehicle’
Example: the USN AN/BLQ-11, formerly the Long-Term Mine Reconnaissance System (LMRS), a torpedo tube-launched and tube-recovered underwater search and survey unmanned undersea vehicle (UUV) capable of performing autonomous minefield reconnaissance as much as 200 kilometers (120 miles) in advance of a host Los Angeles-, Seawolf-, or Virginia-class submarine. LMRS is equipped with both forward-looking sonar and side-scan synthetic aperture sonar. Boeing concluded the detailed design phase of the development project on 31 August 1999. In January 2006, USS Scranton (SSN-756) successfully demonstrated homing and docking of an LMRS UUV system during at-sea testing.