This is coming from a person that was a AWSA member back in college but is not anymore.
The reason I'm not a member is because I don't ski tourneys, thus don't need a membership. I would probably ski in a tourney here or there if 1.) I could get deeper into the course or 2.) If tourneys were cheaper (if the cost wasn't way higher than skiing with my buds with a portable course on public water). To me the key to growing the membership is the first one, increasing the number of high-level skiers and those that grew up competing in the sport. In order to do that, you have to get people hooked while they are young, well before college age.
I used to be of the if-you-build-it-they-will-come attitude. More courses in public places = more skiers. I've changed my tune a bit as I think about it. My local community just built a big outdoor hockey rink, for example, and I'm finding that me and my kids are pretty much the only ones that use it.
I believe the skiing community could benefit from following the recent trends of other sports in the US (select soccer, AAU Basketball, etc.). Parents tend to be very busy and are willing to spend a decent amount of money to send their kids to someone else to get coached. And they seem to be doing so at younger and younger ages. In other words, I think there needs to be more youth-oriented waterski programs that are marketed to anyone that wants to join. At least in my area, I am aware of similar opportunities for show skiing but not three event.
Send the kids to "practice" a couple of times a week and to competitions here and there. Ski behind mommy and daddy's boat on the weekends.
If there are enough of these programs around the country, and they are run well and marketed well, the sport will grow and AWSA membership will grow.