Board Thread:Theories and Speculation/@comment-32369776-20170708034118/@comment-25632268-20170709144341

Well, from all the Senjus and Senju related characters very few had any importance: Hashirama, Tobirama, Tsunade, Mito, Kushina, Naruto

The rest weren't important enough to came up with explanation why they died off (though it is funny considering for Uzumakis Kishimoto at least gave us vague "they were feared because of their Fuinjutsu and killed off")