From: Vermont, USA
It's simple, don't buy those games if you don't want to. I'm not being flip, that's honestly what I'd expect you to do. Both HTTR and KP were at one point retail releases. For that reason, they still are quite present in the secondary market, which favors "bargain bin" prices. The versions out there generally come in retail boxes with old printed manuals and a CD protection system that requires the CD to play. They are also not updated. Still, for some having the printed manual is a significant plus and it's the only way to get it right now for those games as we're out of retail stock ourselves. I'm sure quite a few folks have bought their copies that way and that's fine with us.
Our direct versions are completely up to date with the latest updates and use our no-CD serial system. The retail versions no longer contribute anything to the developers, buying direct from us does. For any of those many reasons, some folks choose to buy direct.
The vast majority of our titles never went retail and are not available through the secondary market. In those cases, the discount here is quite valuable when you consider that you're not going to find them anywhere else any cheaper on a regular basis.