Dan,
I agree with what Adam says.
I don't think anyone questions that Parker has a very reliable palate, nor his willingness to express opinions. What is bad for wine is the extent to which his word is taken as gospel by so many wine buyers, which has, as Adam says, taken a lot of the individuality and quirk out of many wines, leading to a monotone, globalized style of "Parkerized" wine. I want my Bordeaux to taste like it's a Bordeaux, not like another Cal Cab. Now that isn't all Parker's fault, of course, because he has a right to express his opinion and others have a right to follow it. The problem is the fact that he appears to have little time for differing views, or to explain to his audience that those alternative views exist.
Many wine buyers, particularly in the USA buy almost solely based on Parker points (they don't even bother to read his reviews and they think points represent some absolute, rather than just one man's opinion (admittedly one man with a good palate for those who like the styles of wine he likes)). For producers to "follow the market" results in the loss of years of heritage, without those consumers even knowing what it is they are losing. Would you like to see TOC with lakes? I don't want Lafitte to taste like Screaming Eagle, either, or villages Burgundy to try to imitate Californian pinot noir.