It is very rare for performers to do surprise shows for their people. Usually, people must search tirelessly for tickets, and if they can't find one they are out of luck. If the show is a surprise, I think it gives a fair advantage to people who do not typically look on the internet all day long for these tickets. It also shows the performers have a bit of creativity in them, by modifying their tour dates.
Kanye West does not think before he acts and never has. Without any organized plan, he and his managers created a rumour that he was going to perform at a venue in New York. The social media messages that they sent out created a chaotic scene when a mob formed and caused damage to the surrounding area and properties. He proved himself to be once again a disrespectful individual who showed very little consideration to the few fans that he has. It was just a game to him.
Kanye West likes to feel important, and that's okay, but his popup concert was a horrible idea when officials weren't ready for that gathering of people. Okay, so his other concert was cancelled, but was he really thinking about his fans with a potentially dangerous gathering or just looking for more headlines?
Of course hindsight is always 20/20, however authorities should have not allowed this show to take place. Most people are aware of how people react to Kayne West and the mob that sometime follows him. I think incident people where put in harms way by allowing this show to take place.