What makes you want to visit a city? I'd argue public art is instrumental in creating a sense of place, a uniqueness that draws people.
I hiked three miles across the city of Minneapolis to take a photo of the iconic Spoon Bridge. That was no hardship - I like to walk in cities I am visiting, and I like to have a specific destination. Which kind of proves my point: monumental and very visible art creates landmarks and reference points, and brings the city into focus. It interrupts the sameness of cities, in the same way that a focal point in a painting will do.
I wanted to take a photo of the Spoon Bridge, even though there are thousands of better photos of the Spoon Bridge online. I wanted to touch it (visually only!) and make it one of my places, in that way. The Spoon Bridge helps anchor my sense of place and sets Minneapolis apart from other cities I have visited. I've already forgotten the convention center and the airport (even though I am currently sitting in the airport!); the hostel was fine and interesting but could have been a crumbling mansion in any city. The Spoon, though? The Spoon defines the visit, though I was only there for a few minutes, and creates commonality between visitors. It's a shared, and memorable, experience.
Anyway. More public art please, cities! It's always what I remember about my stay.