OK. Please, summarize for me all advantages of mountain bikes over commuter bikes for commuting.

What I've read here:
* they are more light-weight and have lockable suspensions to ride in the streets
* they can't have chain guards, saving a lot of weight
(that full plastic chainguard from Hebie weighs 250 grams
http://www.hebie.de/html/en/detail_s...=0350_S_42_E_1
but the chain is always protected and clean)
* the tires are slow and noisy, but that's OK for short commutes
* the derailleur systems are much superior. All 27 gears can be used, no chain rubbing, no chain crossing, no chain falling.
* the hand brakes are so good that you can safely accelerate going downhill in the streets ignoring any traffic lights and intersections. You can stop in an eyewink.
* mountain bikes allow you to ride at the speed of traffic. It means when the traffic goes uphill, you can go at the speed of 45mph. Why do you need the granny and even the middle chainring?
* American streets are all unpaved and full of potholes. A mountain bike is a must.
* single speed chains and sprockets are more prone to wear than 8 and 9-speed ones
* single-speed chains break all the time making coaster brakes unreliable. Brake cables never break.
* All American women know and understand how to shift derailleur bikes.