Why do single cup coffee makers (ie. Keurig or Tassimo) taste so disgusting ?

The machines have been out for a number of years now. I was initially disturbed by the amount of waste they generate. While it is agreeable to have a fresh cup of coffee to your liking, the awful taste doesn't make up for the personalized coffee drinking experience.

I am trying to convince myself that the bitter taste is from my consciousness. The plastic, paper and aluminum wasted from each serving constructs an image of landfills, incinerators burning dirty fuel, the inefficiency of the factory and the unpleasant factory workers making K-cups that just go to waste all construct the bad taste in my mouth, but no, the coffee just tastes bad.