Well 1 John 2:18 said it was the “last hour”, so it didn’t start with JWs. It probably won’t end with them either.
If they could combine their belief in the end time with a more reasonable approach to equipping their children for life in this system in the meantime, it wouldn’t be so bad. There’s no reason why they can’t retain belief in the end with living a fulfilling life now. So I don’t think it’s the belief in the end in itself that’s the problem. (After all, who can disprove that God will intervene in human history at some point?) It’s the encouragement to give up education, careers, families and good life here and now that is the problem.