The discussion over throughput is valid but there are other aspects that play in this ride.
Putting 4 guests in a single ride vehicle (no train) is needed for the many effects to work for the riders. A long train would possibly raise the capacity but significantly ruin the experience for most riders.
Making the ride much longer is an option but this highly themed ride would cost so much more that I think building another ride in the park would be a better choice as the length probably won't make the ride more fun.
Hype for a ride will eventually die down when newer rides are introduced, you can't make a ride for the popularity of the few opening years. Is a ride longer successful, like Hagrid's', Universal decided to build a new theme park to alleviate the crowds and we win.