That's not so much "evil" as it is "dumb" (pardon the pun). Not knowing the ins and outs of the DVD business, I have to imagine that this release is a combination of two things. One: the DVD box sets sold (relatively) like greased hotcakes. Two: there's a large swath of untapped buyers out there who regularly buy single DVDs but won't buy box sets. And all of that is fine.
But you honestly can't just pick a few "new" shows, even at random, for this disc? A lot of those greased-hotcake-buyers would be beating down your door a second time, instead of wondering why it looks like you might be trying to trick them out of their money (I don't think that's the intention, but it certainly can LOOK like it).