I'll give my condolences to the victims. But, this thread had made cancer, for such an atrocious tragedy.
I respect her for cancelling her tour because I do think that if she continued it, it would affect her and the people in the concert with the idea of "there's a terrorist". It may also say that she's giving respect to the fans who had died instead of quickly moving on and continue her tour. Wouldn't it be implanted on the heads of the parents if Ariana continued her concert, "Does she have respect on the people who died at HER concert?"

If she had reacted on something she can't control, people would give ideas on her like, what's her position for dealing something she can't even deal with? What she can deal with is the safety of her fans and her respect to those people who died. How can we say she can fix this at her current position? She's a teenage girl making records and songs, not a political leader who can order the army for protection.