One of the computer magazines I subscribe to has two subscription rates. One for the regular magazine and then a higher one for the regular magazine with the CD packed full of demos and stuff. Now I understand the difference probably wasn't the CD itself, but the extra cost of shipping.
I used to subscribe without the CD option, but would then read the information about what was on the CD and wish I had it. While I could have picked it up on the newsstand with the CD included, I didn't like making the extra trip and/or would forget about it and miss an issue. So needless to say, I payed the extra money to get the magazine delivered with the CD included. Sometimes it's been worth it, other times I could have gone without and saved the extra couple of bucks.