That's some pretty harsh comment my Guy, I guess even USN doesn't consider them to be "signifincantly inferior"
VL-ASROC > 30km, approximate TOT of 10min to deliver a 50kg warhead
Varunastra > 50km, approximate TOT of 30min to deliver a 250kg warhead
You can either have a fast acting but ship disabling torpedo or a slow but keel breaking torpedo; can't have both so it's up to you.
Is there a reason we still use the Soviet doctrine?
Primary reason is the fact that Soviet doctrine is cheaper compared to the alternative. What's Western doctrine?
For AShW - You've 70 fighters in every CSG, you've 11 such CSG
For primary air-defence - You've 70 fighters in every CSG, you've 11 such CSG
For ASuW - you've a fleet of whopping 50 hunter-killer submarines and yeah, you guessed it right...70 fighters in every CSG, you've 11 such CSG
Everything else you see on in a Western CSG is more or less just to protect these 70 fighters with secondary duty of long ranged fire using TLAMs.
So for a smaller navy who can't afford multiple full-sized carrier strike groups, the Soviet doctrine is quite decent.
Also the fact that we've used Soviet doctrine for so long is also a reason we continue to use it. But I'm pretty sure that after a decade or so we'd have moved away from Soviet to Western doctrine. Something that China has already achieved.