They obviously bought into the same logic that the record companies have for years: "if you make it so that people can have 'our' content on their computers, of course they'll steal it, but if we make it difficult for them, then they won't."
There was a lot of discussion about this on the Christian Gamers Guild list (where I got the info about the White Wolf games response), and generally they agreed all that this does is make the large TSR out of print backlist unavailable, and encourages people to scan and upload their stuff.
I'm not quite ready to go dig out my old TSR stuff, scan it and dump it into bit torrent -- as much because I value my job, reputation, etc. as because I don't like to be a pirate.
But, I'll admit that sometimes I've used backdoor means to get out of print stuff to avoid paying the other kind of pirate (like the people who list used software CDs on fleabay for 10* or more their original price) -- none of which will go to the original rights holder since they were already payed.
The other speculations are that WoTC is planning on opening their own store for download material, and that they are trying to drastically reduce the amount of D&D material available that isn't based on 4th edition. If they are being that mercenary about D&D, then I'll gladly not spend any more money on their products.