One word, 7 letters: Balance.
Sure, it makes no sense in terms of realism and also the IS-2 is probably not in its best spot right now BUT buffing the main cannon damage doesn't make a lot of sense imo.
The IS-2 is tanky as a bull with its insane armor. What it fails to do consistently is hitting stuff.
I remember the time (pre WFA) when the IS-2 was today's King Tiger (maybe a bit weaker), this was not nice and I don't think making it like this again is a good idea.
But buff its accuracy and you got me all in.
Thanks for saying that it makes no sense.
So how far we can go about sense to justify Balance?
I mean, this game isn't starcraft, we can't just create stats and units. They existed and follow some kind of "real world" physics, that's why a 122mm shell can't do the same damage as a 76mm.
Is it better to let IS-2 be equal to all other heavy tanks (tiger,pershing) or be a unique tank that can enter into an asymmetrical balance.
Why is bad that IS-2 have the same "role" as King tiger?