The ride doesn't have any re-rideability. You've ridden it once, you've seen the incoherent movie scenes and you're done with it.
Riders know what they're in for, and they don't view standing out in the sun for 60, 90, 120, whatever it is (once you're beyond 60 in wait time, it makes little difference) minutes worth it.
Maybe if the ride had an actual story, or had some jaw-dropping "holy cats that was cool!" moments in it, that'd be another story. But it's a 'meh' kind of ride, and people aren't going to fall all over themselves re-riding a 'meh' ride.
Believe me, if the Subs didn't have such a poor capacity, you'd be seeing 20min waits instead of 90.