It does appear that they are getting new blood even though he says it is a 62% return rate.
I am guessing the all-inclusiveness of the tours is a big selling factor since other lines do charge for them. Tours in Europe on a 14-day cruise can easily add up to $2000 - $3000 per couple (or even per person). If they give away everything priced at $200 or less that is a pretty significant savings.
I have not sailed on Regent since the 1990s so I cannot comment on the product, but as I recall I enjoyed the trip at the time, and they still have the same ships.