One of the problems with code quality tools is that they tend to overwhelm developers with problems that aren't really problems -- that is, false positives. When false positives occur, developers learn to ignore the output or abandon the tool altogether. FindBugs aims to reduce the number of false positives it reports. Unlike other static analysis tools, FindBugs doesn't focus on style or formatting; it specifically tries to find real bugs or potential performance problems.
For many developers, memory management is at best considered a distraction from the main task of developing business logic -- until the business logic fails to perform as expected or as it had in during testing. When this happens, you need to know what went wrong and why, which means understanding how your application interacts with the underlying computing resources and, in particular, memory. The best way to understand how an application is utilizing memory is to observe the garbage collector in action.