Because doing nothing to serve up justice simply reinforces the behavior. This guy is probably out committing more property crime right now because, hey, it worked last time. Maybe he'll graduate to mugging, at some point.

I'm not going to address your implication that the police are attempting to maximize their market demand. This is an issue of short-sightedness, laziness, and oblivious focus on more glamorous crime in order to placate the electorate.

For more examples of Oakland PD's short-sightedness, look at the enormous crime wave following the Acorn Gang sting. They arrested a bunch of gang leaders, which left the unsupervised lackeys to wreak criminal havoc across the region.