Pros can't wear nice thick fleecey waterproofs and gloves with heating elements.
Why not? You exaggerate for effect, but when the alternative is quitting the race whilst vying for stage win (LL Sanchez) or a GC contendor (Basso), whats 30 seconds kitting/de-kitting with wet weather kit on a 5hr stage? For every "worst day ever" hyperbolic quitter there were 10 finishers. Gilbert crested the first major summit climb first, taking virtual KOM, and apparently didnt even wear arm warmers.
They knew the forecast and possible conditions, and knew they were going to be descending from 2400m, probably on wet roads so unlikely to get dropped by the peleton doing 100kph if they kitted up.
I sound harsher than I am, I follow road racing for the romance, suffering and heroics, but being too cold to control a bike on a descent and being taken away for medical treatment is down to choosing the wrong kit at the wrong time. Notice how many had thermals/arm warmers today? In the spring races everyone wore (often re-badged) Castelli Gabba jerseys as they are race-fit tight but waterproof. Left them back at HQ for the vuelta I assume!
Nico Roche was honest in his interview, effectively saying "it was too cold for me" not "it was too cold".
Not sure pros start the season with much fat, to be honest....