The last time I checked (ca. early 2012), there were tens of thousands of untriaged bugs in the Moz Bugzilla instance. Add to that unresolved bugs in the 3M+ lines code base and multiple platforms supported, and the job is obviously huge. There simply aren't enough people working on such things to keep up.
It is an open source project, so there is something that one can do about such things beyond complaining.
