Why? Bad route or something? I think it was a fascinating race, especially in light of the internal Astana power struggle.
The off-bike stuff was entertaining, but the on-bike stuff was abysmal. You had the last few kilometres of La Grande Motte and the last 40km of the Le Grand Bornand stage (which was great and by far the best stage design Proudhomme had greenlit at the time), but the rest of it was absolute garbage. The Pyrenees were completely neutered to the point where they were effectively sprint stages, then once Ag2r had the jersey and Astana were happy to let them have it, you had a complete week of stages between Arcalis (one of the worst MTFs of all time) and Verbier (not a very interesting climb, only really relevant for the power numbers and Contador stamping his authority over Armstrong) which were completely worthless and in which nothing happened, with the most interesting thing being HTC trying to lead out a sprint whilst simultaneously trying to slow the pace down to get Hincapie into the maillot jaune. Stage 16 looked like it could have got interesting, and resulted in the most impressive thing in Armstrong's comeback when he stamped on the pedals and moved from group 3 to group 2 very quickly indeed, but then everybody sat up and decided they'd prefer it if Dave Zabriskie led the bunch over cat.1 climbs. Grégory Rast led the bunch over the Tourmalet, for crying out loud. The only rider in the top 10 who hadn't been in the top TTT teams all the way back on stage 4 was Christophe le Mevel, and that was cos he'd been in the break that got given loads of time in the middle of week 2.
The route was a major problem with the 2009 Tour, definitely. I think the course was designed with Armstrong's return in mind. The course was actively designed to try to keep him in contention as long as possible because of the additional eyes on the sport. The cleanup job in the previous years had not done wonders for the audience, with Landis' DQ, Rasmussen being ejected in the maillot jaune, Puerto, Telekom, and then AFLD unleashing the CERA test on the world mid-race in 2008. They had no idea how competitive Armstrong could be at that point, having been out of the sport for 3 years and being 37 years old, so they deliberately minimised the selective stages until late in the race and also reintroduced the TTT, not seen since his retirement. Obviously in the end, the Astana team's super strength, that several of those who might have animated the mountain stages were out of form (e.g. Sastre), a number of contenders were undercooked (e.g. Evans, Menchov) or barred (Valverde, due to the detour into Italy) and the fact that post-comeback Lance was pretty good anyway at that point meant it was unnecessary. And the removal of Pierre Bordry from his post, allegedly under pressure from Armstrong fan Nicolas Sarkozy, and AFLD being relieved of the duty of testing at the Tour, has been a move which has had serious long-term implications for the credibility of the sport as well, but that's a tangential and separate issue (and one which is best left to the Clinic really) from why the 2009 Tour is truly the epitome of a bad Grand Tour in recent years.