>The CX bike is taller (more wind resistance),

This seems to be the main point - CX bikes are less designed around aero than road bikes are. You wouldn't see super wide cantis on a road bike...

>puts the rider in a less aero position,

Isn't that just a function of how you set it up? My handlebars are set pretty low compared to my seat. The only real difference should be the slightly raised BB?

>has wider tires (32 mm vs. 25 mm),

As mentioned, you put road bike tyres on to go fast...

>and weighs an extra pound or two

OP specified same weight.

Give me back my free lunch!

Steve