I just finished working through NaNoWriMo. I've had a piece of writing critiqued by a group of writers. I've got one completed second draft in editing. I've got one complete first draft which will not be taken any farther (although I learned a lot from writing it). I've got a nearly-complete first draft that is going to be finished very shortly. I've got the beginnings of a novella due in February.
I've read about 35 novels this year. I've read 6 in the past month. I keep up with about four writerly blogs on a regular basis, and about a dozen others intermittently. I love to read.
So why is it important that I'm a reader and a writer, and how does all of this relate to my opening statement? When you are a reader and a writer, you learn very quickly that a good story shows you things. It doesn't just tell you. A good story will let you use your mind. "Dora was excited about her news" and "Dora's eyes shone and her grin widened as she leaned forward, the words tumbling from her lips in a rush" both let the reader know that Dora was excited. The first way of saying it, though, is kinda boring.
Exposition can be useful in a story, but it can also kill a reader's interest. Have you ever read "Les Miserables"? There are several hundred pages of exposition. I don't recall anything from those pages. I basically ignored them until I got back to the real story. In my critique group, we're very careful about watching for what we call "info dumps" - large sections of exposition that lose a reader's attention. We all try to avoid them, because info dumps are boring.
I watched a play full of exposition. 'Nuff said.