The IS-2 does not face 60 range high pen TDs, comes much earlier as a tech-less callin and is about 30% faster. It gains veterancy much faster and the veterancy bonusses are good.
That's a huge difference compared to the KT. That said though, the IS-2 (and all heavy tanks) needs a main gun overhaul with better accuracy/scatter but spread out AOE profile so it can reliably deal damage to infantry (without wiping squads).
People just want to return those times when almost every KT shot is six people wipe. KT can do that now, but people want to return the Totalalic OP. But at the same time they claim that the IS-2 is absolutely fine, but it is not so: his gun constantly misses in huge blob of infantry or does not penetrate armor. IS-2 just does not cause damage. You practically will not see the 3rd level of the IS-2 veterancy and very often you will see the 3-5th level of the RT veterancy.
These are blatant lies. If you check out the other thread about the KT you will notice the absolute vast majority of people recognizes that the 'old KT' was bad for gameplay but the current version is underpowered and that moderate buffs are needed.
Furthermore the IS-2 and the KT have exactly the same accuracy and scatter stats, and the penetration of the IS-2 is even higher. So your claims that the IS-2 'does not penetrate armor' and 'does not cause damage' are false. The only difference in favor of the KT is that its gun does 240 damage rather than the 160 of the IS-2.
Vet 4-5 KTs are extremely rare due to very high veterancy requirements. If you see them often you're definitely doing something wrong.