This explains a lot. From a reader:

Dear Jonah,
Here’s why Coke Zero is better than Diet Coke: Coke Zero is based on Classic
Coke, while Diet Coke is based on “New Coke” – a drink so bad not even Bill
Cosby’s and “Max Headroom”’s ads could save it:
Some links:
http://leslie.harpold.com/presents/000696demystifying_diet_cokes.html
http://www.bevnet.com/reviews/coke_zero/
A low-calorie toast to you and your family!