On the back of the cover of madden, it tells you this...
Build an online franchise Battle for franchise dominance online with leagues of 32 teams. View standings and stats, make trades, manage depth charts, and more-all from your Xbox 360 or leagues custom web page online.
Does it tell you anywhere on there that you have to pay extra for it? Does it tell you the online code is on the back of the instruction manual? How many people would just walk in, would see a new and a used madden, and buy the used one? Then when they get home they find out they just got hosed.(side note...They do list in the very small and fine print "Paid subscription for online multilayer" But anyone who plays on the 360 would assume that it is referring to your yearly subscription of Live.)
It is good we have the choice to buy new things but when you advertise a feature on the back of the box and then force a customer to pay an additional fee without clearly telling them they will have to pay that fee if they buy it used...Is just wrong. This is a sports game, not a MMRPG(massive multiplayer role playing)
That's partially attributed to Gamestop being so dominant. Unlike movies, games don't have theatrical runs to provide revenue before they hit the home market. When games come out, sales usually almost always drop only weeks after for the next thing. This is magnified even more with the ps3/360 combined total not yet equaling the ps2 install base in its prime years.
Companies feel they should get something from their games selling to more than one customer. That's why you see the rise of Gamestop exclusive preorder stuff that often becomes DLC later on anyways, as it helps encourage buying new. It's not a shock that some DLC evolved into targeting Gamestop new/used customers, but it's not just EA, and they have been on both sides of the dlc price/value spectrum in the past few years.