You are making bad assumptions here. There are legitimate programs distributed this way: I believe BeOS, OpenVMS, and some Linux distros all have official bit-torrents. Then there's [media] releases by independent groups, as mentioned on up-thread, who are literally giving their stuff away. Finally, there's the unfortunate instance where you have a program [possibly outdated] whose master media has become corrupted: should you have to go and buy another copy [assuming you can find one] even if you have all the original disks/packaging/etc?
You are starting with an invalid assumption: that file-sharing is theft. That is as stupid as assuming that the gun's purpose is murder.
When you drive on roads, you're recorded. When you go into stores, you're recorded. It's a question of convenience. You don't want to be watched or recorded? Fine. Don't drive, don't use sites that record your movements. It's not a civil right to be anonymous on the internet.