I think part of the issue, at least for me is limited time. To balance family and work with windsurfing, I only go when it is 10 knots or more (Formula with an 11.0), so if the wind is light, I don't go out. I usually go, sail and come home and don't spend the day at the lake. Got to keep my honey happy.
However, if I had more time or no family, I would be working on light wind freestyle on those non-planing days. You may not want to go out in 5-10 knots, but there are plenty that do.
Back in the mid 80's when the crowds were really big, the experts and beginners were all out on the light wind days on their long boards. Those with the skills would "show off" their tricks to the beginners by doing pivot jibes, back to sail, helicopter tacks, sail 360's, rail rides or more advanced freestyle skills. In my first couple of years of windsurfing, I remember how impressed I was at the longboard freestyle skills some of the sailors had. I was not intimidated, just excited about the possibilites with some practice.
When the winds picked up, the few that had shortboards were out and many others were on their "transition boards", learning short board skills. There were and are still, more light wind weekends than there are windy weekends. I live in Dallas, Texas by the way. Lots of lakes (reservoirs) to sail on - 6 within 45 minutes of my house.
Racing was big in the 80's because the typical local regatta was in light wind and we all had long boards. In many ways, racing long boards in light winds was very challenging and fun. Subtle performance sailing techniques made the difference between winning and losing and just about everyone could race, regardless of skill.
Many of our local regattas in the past few years were run in light winds, much like the 80's, only fewer long boards. I still race my 1985 Mistral Superlight with the original 6.3 regatta sail in these light wind races. Great fun and I love to "kick butt" with my 23 year old gear.
In Dallas today, I would say that windsurfing is growing just a little, but nothing like it was 25 years ago.
For what it's worth -