Heres why:
Quoted directly from Consumer Report's 2005 Buying Guide, here are their comments and ratings for the Trailblazer:
Comments: "This SUV is quiet and spacious, with a compliant low-speed ride. The vehicle falls short due to sloppy handling, uncomfortable seats, ill-fitting trim, and too much wind noise. A longer EXT model has a third-row seat. The annoying seat-mounted front safety belts can pull down uncomfortably and are hard to reach."
Predicted Reliability: 1/5 (much worse than average)
Depreciation: 3/5 (average)
Recommended: No
Also ranked second to last among mid-sized SUVs.