In their eyes you aren't a customer if you buy the game used. Which is 100% correct. How is a developer trying to recoup some cost BS? It's not at the expense of people giving them money aka the customer.
-Not really a signifigant amount since people will primarily buy it for multiplayer.
-On PS3 it works on all accounts active on it the HDD. Don't know about Xbox.
I rarely buy used since new games have gone on sale at such low prices as of last year. So I don't have an issue with online passes. In fact online passes encourage me not to buy used.