The way David Simon explained it, I thought the "real" point of the show was to portray an American city in all of its glory and all of its shortcomings; to show what causes systemic failures in its institutions.
yep. I believe season 5 was the actual darling of the creators--being the Simon spent many years working for the Herald (or Sun? forget what it is/was in Baltimore)
that season was sort of a black sheep as well, as it focused more on journalism and the newspaper industry as a whole--not really about the drugs and money, but the inherent limitations, the rampant failures, and the degradation of journalism, forecasting the rise of the blogosphere. It was quite prescient, as the concept for the season was fleshed out before the major news organizations really started to feel pressure from the web.
IIRC, they were given a short order for that season, so it ended up a few episodes shorter than desired. Still, it ended perfectly and probably remains the best visualization of moral and economic bankruptcy in our contemporary institutions.