Full disclosure, I live on a private lake however I'm always happy to bring along guests/friends/random people I meet who are interested in skiing. I am a terrible skier but I really enjoy trying to get through the course - not that I can.
Personally I think a big way to build the sport is through tournaments. The big problem is that most people have no idea what that is, where/when they are happening and what to expect. Our lake hosts 2-3 tournaments every summer. I had never seen a tournament, nor even thought about it until I moved onto the lake. Watching great skiers is an amazing experience. The public is welcome to attend but does anyone show up? NOPE! The issue is advertising, no one, unless they are a part of the skiing community has any idea what is happening. Every time I have a friend over at my house and someone is out skiing the course they are amazed by it and are honestly interested in skiing. Washington state has many private ski lakes, many of which offer "reasonable" memberships. They also have regular tournaments but I can imagine that they rarely if ever have spectators.
Waterskiing has almost no TV presence and no advertising for the masses. Most course skiing is largely limited to private lakes. If we want to grow the sport, the general public have to know what tournament skiing is and make it enjoyable for spectators. If we create a positive environment and can then improve access our sport will grow.
Wakeboarding/surfing is more tolerable in rough open water and there is way more public awareness of those sports. If watersking wants to grow, we need to get the word out and make it grow.
Just my 2c.