It might be because you are used to tea bags.

I have had a few British friends who turned up their noses at tea bags and claim that the only way to get a good cup of tea is to follow a tea brewing ritual with loose tea.

I do not think that coffee bags make a "bad" cup of coffee. I just think that the coffee in the bag isn't all that great to begin with.

When car camping, I use a Lexan French press that will make an excellent cup of Joe if you start out with good coffee, but coffee bags are real handy for light travel and they sure beat instant.

Anyway, great question. I too would like to hear what the coffee police have to say about this.