Archived link since the site has been, ahem, brutalized:
There isn't really an argument for brutalism except laziness and the usual contempt the design community has for its end users. Minimalism has its place, as does maximalism, depending on the context within the application. But that requires actual thinking and then both taste and skill, respectively. Much easier to just wallow in contempt with occasional outbursts of sarcastic novelty, as architecture has done for the last sixty years.