I support the idea of cracking down on used game sales, here's why:
Look at other medias like movies, books and music.
Movies - the film-makers get a fat sack of cash from a studio to make their film, and when it's done it's licensed to theaters and makes money there. It's then licensed to DVD/Blu-Ray and makes money there, also rental stores. It's THEN licensed to pay-per-view blockbuster TV channels, and online services such as NetFlix. It's THEN licensed to free TV.
So effectively the movie has been sold five times to five different mediums - used DVD sales are rampant but that doesn't matter because the movie is still producing cash all across the entire world.
Books - cheap to write, cheap to produce, sell for a huge markup from that production cost. If the writer is successful, they can then cash in on merchandise, signings, even movie deals if they do well enough (Harry Potter), and the process goes up to my first point.
Music - a little more complicated because the RIAA can fuck off, but some artists make ridiculous amounts of money off their music in more ways than album sales. Merchandise and shows are huge, plus endorsements and advertisements - how a musician makes their money is limited by their imagination and personality. Taylor Swift made $80,000,000 in the past two years, plus $100,000,000 revenue (not all hers) from her recent world tour - and almost none of that was from album sales.
Games - developer has capital, makes game, sends to stores and online services like Steam.
That's it. End of profit.
They don't get their money anywhere else except in a few rare exceptions. There aren't shows, there's very few merchandising options, and they need that profit to be able to have jobs next month and to create new content.
This is why games are made over and over, like CoD and EA Sports, and why publishers ruin games. They want it guaranteed to sell as much as possible because new copies are all the income they get, while used game sales and piracy hurt their bottom line and thus jack up prices.
As a gamer and also retail businessman, I say I don't care about stores. The evolution of technology is making stores and physical copies obsolete, when you can download games directly to your PC and Xbox through services like Steam and the Live Marketplace.
Who wants to go out and give a store a cut of the price of a game when you can have it ready to play by leaving your PC on overnight downloading as many titles as you want? Plus doing that, you get automatic updates, instant DLC, tech support and instant access to that game's fan community.
The only situation in which I'd support buying a used game is if there literally are no new copies on the shelves or anywhere else to buy because they simply don't stock it anymore. You shouldn't be entitled to a cheaper product just because you can't afford a new one.
tl;dr - used game sales hurt game developers that are irrelevant to other medias, down with stores and up with Steam.