Because you're smarter than average porn customer.
Not everyone want to use torrents to find out what they want.
Also, some content cannot be found for free...maybe after few years
Porn doesnt sell as it used to but still a big market and plenty of paying happy customers!
Software can be found for free. Cinema movies can be found for free but that doesnt mean both industry are going to vanish anytime soon :D
Somebody need to pay for it to make it available for free! Simple logic...