Yeah, this is pretty freaking easy: yanking the PDFs was a business decision. Whether it was to properly defend the IP, piracy cutting into dead-tree sales, fear of older edition sales undermining the new edition, or all of the above, it was a business decision, pure and simple. The official line is that it is was piracy. Maybe it was, maybe it wasn't. The bottom line is that it was all about WotC's, uh., bottom line.
You guys can concoct all the theories you want and it doesn't matter. Even if they did "come clean" and explain why, it would serve no purpose, Mod Edit: Grandma thinks you've gone a touch too far. If you need to use that kind of imagery, methinks you need to chill out.
Now personally, I don't think it was a very good decision, as I'd certainly be spending some money rounding out the PDF collection of the old TSR titles, which is more than the zero dollars I've spent since they were pulled the PDFs. And no, that isn't some sort of protest, I'm just not their target demographic for the current edition, and unlike some, I don't think they killed my dawg or anything - my old stuff is right there, on the shelf for me to use and I'm still having a blast with it.
But whatever, the income generated by the PDF sales wasn't enough to justify the continuation of the program, and thats all there is to it. Maybe we'll luck out and they'll be put back on sale in the future, but this impotent wailing and gnashing of the teeth, while entertaining in a "look at spoiled brat" kinda way, is pathetic.