Whether or not game prices are too high is one thing. I'm sure there can be a healthy debate on that subject. But I don't think any reasonable person can conclude that game prices are not at least prohibitively expensive for the purposes of impulse buying. The moments when you just happen to be in a store and see a new game on the shelf you weren't planning to buy yet figured "what the hell" for one reason or another. I have a rather large collection of games yet I can count my full price impulse buys on one hand. Used impulse buys, however, are a different story.
Clearly people like used games. If they didn't then there wouldn't be such boisterous outrage over many of Gamestop's practices. Who cares if Gamestop puts stickers all over used games if you only buy new ones? Games might not be too expensive but they certainly aren't inexpensive. Even if you eliminate impulse buying from the equation, buying every game you want to play brand new will get very costly very fast if you want to play more than a few games each year. I don't know of anybody who isn't at least a little discriminatory with what games to buy at full price.