People won't attack because teams are too strong these days. Let's say, for the sake of absurd argument, that the whole Silence-Lotto team attacked on the Tourmalet. On the lower slopes, they gun it and get a gap, like they are team trialing up the mountain. Only Astana chases and everyone else who can hold the pace follows. It is Astana versus Silence. Who burns out first? Silence does. Their riders fall away, the pace drops, and in the end they are caught by team Astana, which may be fatigued but not as fatigued as Evans.
If Evans' whole team has not got a chance then what chance does a solo attack from Evans have? Evans gets to ride solo at FTP while Astana riders take turns riding at 110% of their FTP. That just is not going to work.
Ideally Silence, Saxo, and Cervelo would collude on a climb to set a pace so high that everyone but the GC contenders is burned off. Even then the remaining group is four Astanas (maybe only three now), a contender from each of the other teams, and a handful of climbing specialists. The GC contenders then take their chances, knowing that those chances are slim because the Astanas have more legit contenders than the other teams' GC men combined. That is a crap shoot with low odds, and when a rider craps out he drops from the top ten in Paris. It is safer, and perhaps a smarter financial choice, to just take your top ten and hope things turn out different the next year.
I personally blame doping for the strength and recovery ability of the teams. To compensate, teams should be smaller. Use six man teams and see what the difference is. Even a team like Astana would be forced to use Kloden and Levi if they wanted to protect Contador and Armstrong.
Dang, I am rambling here.