I have a Nespresso machine which as you know is a pod machine, the coffee is completely sealed in an aluminium pod. How does air get to the coffee in the pod here?
Also, the machine 'produces' (is that the right word) 19bar which Nespresso think is the correct pressure.
Remember, Nespresso are coffee makers, not coffee machine makers. They get Migimix and Krups to make the machines, while they concentrate only on the coffee (which is very very good by the way!)
I'm not totally up to speed on the actual processes that Nespresso use to get the coffee in the pods. From my experience if I grind fresh coffee and vacuum seal into a bag and compare to whole beans sealed at the same time, the difference when made is dramatic even for the uninitiated.
Good espresso is extracted using 9bar of pressure, to produce 25-30mls in 25-30 secs. Nespresso probably use 19bar to try and get as much flavour out of the pod as possible.
Nespresso has it's place, just like the Guinness widget has it's place. It's not going to give you the same experience you'd expect from a cafe or from using decent equipment at home.
Another negative associated with pods is that coffee is a perishable that needs to be used within a certain window. Sucking the air out does not improve its shelf life from 1 month to 12 months.
On a positive note, Nespresso introduces the consumer to more coffee experiences, through different roasting profiles and more importantly different single origins.