If I go out and pirate Spore instead of buying it, I just decreased their sales. I stole it instead of buying it.
Now if you want to argue that the people pirating would never have bought the game, then file. It doesn't decrease sales in that respect. It is, however, still illegal. If the game companies don't do anything about it, then the government should.
Well I wish I had pirated Spore. Instead I bought it.
But if I had known about the max 3 installs and the little program it installed on my pc that was allmost impossible to get rid of I might have pirated it instead. And THEN delete it:)