I agree with you, faster cadence = better riding but I think we do it for a variety of reasons. It's better for your knees for one! grinding( turning the crank slowly) is not unaptly named, as it's what your doing to your joints , which can cause health problems in years to come; and it's also grinding your gears away! High Cadence (spinning the crank quickly) makes it easier to make a smooth circle, keeping your power more even and the demands on your body and bike more evenly spread. With a higher rpm your better prepared for changes in terrian, being able to slow your cadence or smoothly shift up a gear.
Aerobic fitness as I understand, is your effort levels where your lungs are able to keep up the supply of oxygen to the blood and this fuels your muscles. If you go beyond this capacity, your body starts burning reserves to make up the shortfall.
Oh well, the bike's white so at least I could see where the muck was to clean it off!
This is in addition to the 10 percent that I get for being a team performance member. If they included Shimano components in this sale I could be in trouble. 
I still might get a pair of their "cool black" ultra bibs I have had my eyes on. They are already on sale and with the discount, hard to resist.
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Won't be able to sleep later unless I know. 
