Dudes like stuff.
They like other dudes stuff, they like to look at stuff, they especially like to buy stuff the crazy thing is they like to buy stuff for there characters as much as for themselves. All the stuff is just fluff. People are what make gaming worth it. If you played Rifts (which I'm only using as an example because I missed the whole d20 cluster frak) did it really matter if you had the South America book while playing a game based in France, um ... probably not, even though there was that cool piece of armor in the book you didn't have. Yes we all remember the coolest thing our one great character absconded with, but was it as important as the afternoon you spent adventuring? Not in my mind anyway.