They haven't found the footage to make many extended episodes; money probably wouldn't solve that problem. Agreed about the lack of commentaries, though. CBS is just being cheap by not including them. Considering that The Prisoner
, made twenty years before Star Trek: The Next Generation
, managed to include commentaries on seven (out of 17) episodes, there's really no reason why they couldn't get together more than a few people in a recording studio for this.