When you are a professional and are riding for six hours in the middle of a pack of 120 or so riders, and are getting pulled along in the giant vacuum of all those people, aero don't mean much.
If you are a studly domestique who is the breakway rider du jour who will zip along for 100km or so until you get swallowed up by the pack, it will mean a little. But 100 riders together is a heckuva lot more aero.
If you are world class riding against the clock hundreths of a second matter. But you still have to have the engine.
Bike racing is a lot like golf...you can't go to the shop and buy speed or low scores with equipment.