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.
I'll wait till I've reviewed the entire season in motion on my home cinema system before calling it - but, I must admit, based on the evidence thus far presented, it's looking like this set will fall short of the exemplary standards set by season one.