How do author’s maximize emotion when writing scenes?

A few years back while attending a writing workshop in intermediate fiction at Denver’s Lighthouse Writers Workshop I learned a technique for writing with emotion. The instructor, Doug Kurtz, stuck out his palm with a stack of index cards and asked all of us students to take a card, read it, and place it upside down on the table. 

Each card held an emotion - anger, fear, sympathy, etc.  He gave us a scenario to write about and asked us to write for 10 minutes using the emotion that was listed on our card.

The exercise taught me to feel what my characters are going through while I write a particular scene. It is my belief than many of us author’s struggle with the concept of inserting emotion into our writing. In my chosen genre, thrillers, I read all the bestsellers and see varying degrees of emotion in their writing.

When I switch to literary fiction I find plentiful use of character emotions. Is this because in mysteries and thrillers the author is concentrating on action and plot, and to a lesser extent the emotions of the characters, or is it because in thrillers we are struggling to keep the content moving forward, and the use of too much emotion bogs down the pace of the writing?

What do you think?