Though the DS's do have maps to the course, weather forecasts, and a lot of other information, it is not possible for them to prepare for every eventuality. This is especially true when it comes to the weather.
Regarding the TA overgearing issue, the riders were able to crest the steepest climbs, but some stated that it was not possible to stand on the pedals without the rear wheel slipping out on the wet road. a 30 percent gradient is an out-lyer by "normal" standards, and would have posed a serious challenge even in dry conditions. The race promoter of TA was enough of a gentleman and sportsman to apologize to the peleton for the overly-difficult terrain he chose. I thought that was a real act of class on his part.
As for clothing chocies, I am certain that each rider had the option of bundling up as much as he wanted prior to MSR. Again, the weather was far from normal and (as anyone who has ever trained or race in northern climates) sometimes the weather wins no matter how prepared and well-equipped the teams are.