Sir John, whose club became the first English team to reach the last four but lost 12-9 to Agen on Saturday, believes the competition is a costly non-event.
Newcastle chartered their own plane for their overnight stay in the French town and Hall said: "Everybody is losing a fortune in the Conference. There is not enough money, and the travelling is expensive. We're just totting up, but coming here has probably cost us pounds 10,000. We get a bit back, but there is not enough money in the Conference for English clubs.
"We're not being greedy - it's just a fact of life. The European Cup needs revamping, and I don't think there is a place for the Conference. There has never been much coverage, and TV doesn't want to know."
Rob Andrew, Newcastle's director of rugby who scored all his side's points with three first-half penalties, said: "The Conference has been a good competition. There are a lot of very good sides, but it has had no marketing and very little exposure," said Andrew.
"I think it has a future in some form or other but I'm not quite sure what. I would like to see more First Division clubs in the Heineken Cup.