I have always believed that "upturns" and "downturns" in the numbers of people sailing and its apparent popularity, has always been dependent on economics rather than "technology" or "innovative" designs of craft.
There was a massive upturn in numbers of people sailing "off the beach" craft throughout the 1950's when the economic resesive times of the second world war were finally at an end and people were seeing real "affluence" for the first time since before the depression of 1929. There was a big downturn in numbers sailing throughout the early to mid sixties due to a world mini recession. the mid to late sixties through the 70's, during the times of "flower power" carefree attitudes, full employment, abundance of "readies" and relatively "cheap" manufacturing costs, etc, saw the largest upturn in numbers of people taking up sailing than had ever been seen before in history (and never seen in those numbers since). This was the time that Hobie took off due (I feel) to their "differences" from other craft of the time, due to their color, which had never been seen before in sailing craft, but mainly due to their ready availability from retail outlets all around the world (thanks to the deal that saw Colman take over the responsibilitys of manufacture and marketting and leave Hobie Alter with a very comfortable "royalty" to sit back and enjoy life) although others tried to emulate "Hobie", none were as successful as the "first cab off the rank". There has been a major decline in numbers sailing from the mid 80's through to the mid to late 90's with "hard times" felt in most western countries during that time, ie high interest rates, poor balance of payments, social/political unrest, stockmarket crash, etc etc, but from the late 90's, as time have improved and money has become more available to a greater number of the "ordinary" people, we have seen a gradual upward turn around, up to and including the present, of people sailing. I only hope that this trend continues for many years to come. If one looks at a graph of the "activity" in the real estate market over the last 50 years and then compare it to a graph of the numbers of people sailing you will find that they are almost identical in their movements.