That "just" did not mean "merely." It meant doing justice to the work at hand and to the culture in which it appeared. Another way of putting that is that he wrote with a blogger's alacrity but with a thoughtful critic's sense of responsibility to, yes, "the great tradition" the author aspired to join.
Think also of Edmund Wilson, the best book reviewer this country ever had -- alert to the possibilities, both moral and aesthetic, of the "classics and commercial" (to invoke the title of one of his collections) that passed before him. His method was usually rather reportorial -- generally he let his opinions emerge indirectly, not as fiats but as muted implications of the way he read (and quoted) the work at hand. He was not a showy, or even particularly quotable, critic. But the clarity of his prose remains exemplary.
Finally, there was George Orwell, scrambling to make a living by writing reviews for London's intellectual press for maybe $20 or $30 a piece. He was more pointedly political than Wilson, and more attuned, perhaps, to the vagaries of trash culture, but his defense of honest vernacular prose in the face of bureaucratic (and totalitarian) obfuscation remains a critical beacon.
All of these men wrote ceaselessly, against deadlines and under economic pressure, without succumbing to the temptation of merely popping off or showing off. None of these men affected the supercilious high Mandarin manner of, say, George Jean Nathan -- as annoying in its way as hairy-chested populism is in its.
And all three wrote for intelligent readers who emerged from their reviews grateful to know more than they did when they started to read, grateful for their encounter with a serious and, indeed, superior, mind. We do not -- maybe I ought to make that "should not" -- read to confirm our own prejudices and stupidity.
I don't think it's impossible for bloggers to write intelligent reviews. I do think, however, that a simple "love" of reading (or movie-going or whatever) is an insufficient qualification for the job. That way often leads to cultishness (see the currently inflated reputations of Philip K. Dick or Cornell Woolrich, both easy reads for lazy, word-addicted minds).
And we have to find in the work of reviewers something more than idle opinion-mongering. We need to see something other than flash, egotism and self-importance. We need to see their credentials. And they need to prove, not merely assert, their right to an opinion.