Because you feel people that write software shouldn't be able to feed their kids? No, really... programming is work, for lots of people. What do you do for a living? How would you feel if I said I'd never pay for that service, or the goods you manufacture, but would instead prefer to steal them?

Software doesn't write itself. Even opensource software is written by people who are taking their own time and energy to write it and then donating it for free to the world. In order to do that, they have to support themselves, usually by writing software in the business world, which charges for software. If you don't buy software, they're out of a job. If that happens enough, free software will vanish as well.

Btw: You did pay for software already. Just owning an N900 means you paid for the software on your device when it shipped. Assuming you didn't lift an N900 from a retail store...