Elephant is very vulnerable to guards or shrek carrying squads. What you mean to say is that it takes a while to kill them. But who cares, they move slowly anyway they are not going to get away. The elephant needs heavy armor because it is a dedicated tank destroyer. And the rear hit thing is patently false. One t34 can defeat an unsupported elephant easily. The elephant gives the German player more time because they are not used for the same thing. Even a single conscript squad given enough time can bring down an elephant with at nades.
Yes, given infinite amounts of time and resources, one conscript squad can take down an elephant. However, this is completely irrelevant in the actual game. A soviet player quickly loses his ISU152 when caught off-guard. A german player has much more time to save his elephant from destruction. Having your 100 range tank flanked and isolated means you committed a huge tactical failure and it should result in a quick death of the tank. Currently this is the case for the ISU152, it's not for the elephant. The huge HP pool combined with the highest armor in the game gives the german player way too much time to respond compared to a soviet player in a similar situation.