Just a guess, but when I quit smoking about ten years ago, places to smoke were already becoming slim to none in some environments. The one place I wanted to keep smoking OK was, of course, my own home. When I am on vacation, my hotel room of ship's suite takes the place of my own home. This was sort of my "last line of defense" as a smoker. So it is Regent's ban on smoking in ALL suites that I feel is a bit draconean on smokers -- as I remember back to when I was one of them.
No doubt, the designation of a block of smoking rooms on all of Regent's ships might result in a degree of "booking inflexibility" on some cruises, that might result in some vacant suites. But isn't (or wasn't) Regent all about customer service, above all?