[mossguy]

I believe that holding the mug in your hand signifies to your brain that you are reasonably relaxed, enough to take the time to actually enjoy the coffee. The mug provides a sens of permanence and reliability (needs a better word).

A paper cup tells your brain to hurry up, do something else while you are drinking coffee, multi-task, don't get further behind, etc., etc.

I am typing this while I am enjoying another cup of coffee in my favorite mug!

Best,
Tom