The Langster is so expensive because while it's a bottom of the line street track ride, it's still not Wal Mart quality. Really, what is it you're saving on? An extra chainring or two (which will probably be stamped on anything costing less than $500), a rear cassette (like $20), and some derailleurs (another $20 or $25). Grand total in savings: less than $50.

$600 is overpriced for the Langster, by the way. At the more realistic $450 or $500 it's not a bad price for what you do get (apart from the rear hub which apparently has some real issues).

Other than that, I get the impression that people hate it because not only is it an inexpensive complete street track ride (thus making it easy for the novice to bite some cool) but they're ridiculously late to the game. They'd be bandwagon jumpers if the bandwagon hadn't already passed them by.