No story equals no depth or substance
Crackdown takes the open world sand box concept of GTA and removes any semblance of story from it. It tries to focus exclusively on mayhem, and the result is a bland game whose objectives lack context and repetitive one-dimensional missions.
The game itself has more dimensions to it, insofar as there are varied side missions, but I find that in general side missions complement the main story campaign of a game, and on that front Crackdown was completely lacking. By the end I found it almost a tedious effort to get to the end of the main campaign so that I could declare the game “completed”. I had plenty of other things to do in the game, but after 15 hours or so playing I really didn’t want to touch it ever again.