There have been a number of good comments already that I agree with.
Only a few would. Here are a few reasons.
- There is a difference between an isolated cult and one that integrates with society as the Watchtower does, and hence it looses some of its power.
- The main teaching of the Watchtower is living forever, not dying to get a reward. They would need to change the message before insisting on suicide.
- Blood transfusions are not quite the same, as they convince followers that blood transfusions are more dangerous than refusing blood.
- Many JWs do not believe it, they just go along as it is part of their family culture. The Watchtower has been around too long and is now too big.
Maybe in Russell's time there would have been more chance to get a group to suicide on October 2nd 1914, as at that stage they were far closer to the parameters required for a suicide cult.