Dude. Mp3s don't pop out of nowhere when a band writes a song. We have places called studios where musicians get together and twiddle knobs and stuff and make RECORDINGS, which get pressed onto CDs and encoded into mp3s. I wonder why it's called the RECORDING INDUSTRY. Maybe because it makes all those RECORDINGS you share online.
ARTISTS DO NOT MAKE ALL THEIR MONEY AT CONCERTS. They almost always get a buck per unit sold, usually more, and if they are on a very small label or produce a record by themselves, they get a very large cut. Bands that aren't really popular yet (and signed to a RECORD label) don't make shit playing live because they can only book little venues at flat rates or like $4 a head, or they open for bigger acts who don't give them very large cuts anyway. Until they get signed by a major label (the ones that make the famous RECORDINGS), their revenue comes from CD and merch sales, and they play live to get their name out so more people will want to buy their music. Poison was playing and filling enormous venues in Los Angeles before they got signed, and they didn't make enough money to keep themselves fed (they had groupies buy them stuff) because they didn't have an album.
Get it? RECORD SALES ARE IMPORTANT. BANDS THAT ARE NOT SIGNED TO CONTRACTS TO PRODUCE CDs DO NOT GET THEIR MUSIC SOLD ONLINE, DO NOT MAKE MONEY PLAYING LIVE, AND DEPEND ON THOSE LITTLE PLASTIC CIRCLES TO MAKE THEIR CAREERS PROFITABLE. PHYSICALLY DISTRIBUTED RECORDINGS MAKE THE WORLD GO AROUND. DOESN'T ANYONE FUCKING GET IT?
And before anyone bitches at me for having an enormous mp3 collection, I also own 200 CDs, I buy more frequently, and over half of my mp3s are from albums I have paid for. Yes, I also have them shared online, but it's not my job to police people and keep them from downloading songs they haven't paid for.
EDIT: Even once a band makes it big and they do make a majority of their profits from live shows, that doesn't mean CDs aren't a piece of the pie. Wouldn't you be pissed if a third or a quarter of your annual income was in jeopardy?