Aero is basically the only thing that matters, second only to recruiting freak-show riders with horse lungs. These guys are averaging 40km/h. Have you seen Vingegaard's ridiculous mushroom helmet that's pushing the boundary between headwear and faring?
This is just what the bike companies are selling right now since an Aero bike with disc brakes and electronic components that comes in at the UCI weight limit is like $15,000.
If you can have it all you want it all.
Aero doesn't matter at all on hill climbs, they are going too slow there for that.
That wasn't the question. The question would be whether a team would trade mass for drag and the answer is clearly yes. Every elite team has lighter and heavier bikes that are suited to different events.
from GP:
> Team Sky said that during a time trial stage bikes might be heavier to allow for better aerodynamic performance
(emphasis mine)
TDF time trials are almost never uphill. And yes, they have different bikes, showing that that while they might trade mass for drag during a time trial stage, they would do the opposite for hill climb stages. So "aero is the only thing that matters" is clearly false.