I suppose some people interpret a bike bell as being the cycling equivalent of a motorist blasting their horn at someone that they consider to be in their way, rather than just a friendly warning that there is a cyclist approaching. Bikes can be almost silent, and a lot of pedestrians lack any awareness of their surroundings. I'm not sure why a pedestrian wouldn't appreciate an audible warning. I guess some people just lack any kind of hazard awareness. They probably open car doors without looking too.