I think you are seeing a lot of programs that traditionally don't down-cycle for long periods of time going on extended and concurrent down-cycles. SLU just went through 3 consecutive losing seasons for the first time in decades, GWU has had some internal strife which coincided with some down seasons. UMass has one NCAA tournament appearance in the last 20 years and has had 4 losing seasons in a row. Richmond has had two losing seasons in a row and no NCAA tournament appearances since 2011. SJU has had a couple down seasons by their standards.
Couple those with George Mason not having great performances since entering the league and the size of Davidson (1,800 students), along with the loss of some interesting rivalries and I can understand some lagging fan interest.
The good news is SLU looks like we are starting to rebuild, Dayton (which has never lagged in participation) looks like they are building very well, VCU is rock solid, Duquesne is improving, UMass looks solid, Mason and Richmond have started strong this year, even Fordham currently sits at 3-0. I think stronger programs will lead to more enthusiasm and more participation going forward.