I think the problem is different, lets see some example.
- If someone cannot afford the books, and they pirate, good, because they may just then BUY the actual books, they sure as hell will not, otherwise. Piracy = free advertizing! Computer game companies know that (but won't admit it). Also, see how Electornics Art were forced to back down from their asinine DRM garbage last month, as fans hammered them for it, it ruined sales and never stopped piracy.
You don't have money to buy most books, so you team up with fellow polish players to buy PDFs and share in community who are poor.
Wizards see 1:5 ratio of owned / user books there.
You also run a lot of demo games, where when you have to you share books. You can show about 1000 people playing in these games. Most of them start buying D&D products.
Maybe not the PDFs the DM of demo game had to send them, but a LOT of books.
And you get an 1:10 ratio on PDFs and for every pirated PDF a LOT of extra hardcopy sales, since these demo groups attracted loyal customers.
Baad baaad pirate dm, he not only pirates books but uses it a lot of time, even to promote the game in new communities which create extra sales.
But even this scenario says: PDF sales are unfair.
Why?
If only 10% pays for them, and the 90% doesn't and yet it is good for the game, Wizards can check: what would happen if people would pay for hardcopies, services, etc. but PDF releases for demo groups would be free, and would come with a delay (so people who want to be in the first few to own a book should choose the hardcopy)?
If the later would mean far more new customers and far more profit than the current 1:10 ratio, then I would pull sales of all PDFs from all vendors, and then just offer the PDF for free later (would check if 3E is good or bad business, and if it is bad, it would be 4e only).