They tackle it up front in the movie. Not everyone hates and fears him . Some do,yes. But most of the world had started to become reliant and trust and even worship Superman.It would make sense that a majority of the people who lived near ground zero of the Black Zero event,who came the closest to being wiped off the face of the Planet first,would want to honor the guy who stopped that. Besides,it wasn't solely a tribute to Superman. It was a memorial to the victims and the military,police,etc who died that day. It was called "Heroes park". It would make sense that Metropolis' resident hero figure would be the symbolic focal point of such a monument.