My questions is: What is the reason that this is not how the pool operates? It would be a win for the operator (more profit), and a win for all miners, because the opportunity to do pooled mine at 0% fee would attract many miners. So, if the information provided earlier is correct, this would be a win-win situation.
I can give you the reasons why I don't do it, but understand that there is no right approach. Anyone can do whatever scratches their own person itch. The pool is designed to protect alt coin chains via merge mining and to distribute these coins to users who want to get them via mining. Their use of the coins will hopefully (if they don't immediately sell) help with the exchange rate of the coins. If I were to only provide bitcoin and receive fees via selling the alt coins then my selling would dump the alt coin market and drop their prices quite a bit. I'd also be tied to the risk that the alt coin prices drop, or the alt coins fail, making the pool lose money while offering a zero percent fee.
This is the last 'justification' post I'm going to contribute to this thread because it's completely unproductive. Any answer is a 'right' answer depending on individual miners wants and needs. That's why it's great having so many pools to choose from.