I play console games on the PS3. I buy both new and used games, and never sell any of them once they are on my shelf. My latest purchase happens to be Skyrim. I only purchased it because my friends hounded me for weeks with "Dude you gotta get Skyrim it's so cool"-type comments, so I rented it from Redbox for a 1 day. I bought the game new the following day. I otherwise would not have and was prepared to go without ever playing the game until I rented it, and started getting curious about the story. Many of the new games that I buy, have similar stories behind them. They start out being rented, borrowed, or on occasion demo'd first, then turn into a sale.
Most of the games that I buy used, are impulse buys while I am at the store to get the new game. They are typically games that I would never buy new (and some quite frankly I would never miss if used games didn't exist).
The point I'm trying to make is:
1) Without the ability to play used games, I would not have purchased the large majority of my new games due to the uncertainty of whether I am going to like it or not, leading to less revenue for the publisher/developer.
2) The used games that I buy are not titles that I would ever consider buying new. I'm usually looking for that gem that nobody knows about, including myself. They are the games that have the 6 price labels on top of each other that have been in the store so long that they are probably costing the retail store money by taking up a spot that a good game could be displayed. They typically turn out to be games that had good reason for sitting there so long. They are the games that are basically individually packaged shiny coasters. They are the games that would have never translated into money for the developer or publisher, because I would have never bought it except "Hey, why not? I've spent more on a cup of coffee". I see my used game purchases having little effect at all. Maybe you can take some comfort in the fact that I just took a used game off of the market, to sit on my shelf forever.
I realize that this isn't the circumstance for every person that buys used games, and that some people are going to buy/trade used games exclusively, because they are cheaper. (The good or popular ones don't seem to be that much cheaper though.) This is probably not the situation with even the majority of used game buyers. It is my situation, as a casual gamer. I have to believe that there are many more casual gamers that would skip the console experience altogether (or stick to the ones we currently have) if the Non-used game console ever happened.
You know what the saddest part is? It probably will happen .... eventually. Then, even if all of the gamers united and boycotted the console(s) that implemented it, the publishers and devs would probably just use the other scapegoat to explain the lost sales. The Jolly Roger! And SOPA, the "Stop On-line Privacy Act" will resurface in one form or another...yet again.