Hopefully Disney has done a better job designing adequate capacity into the rides that will be opening shortly. Obviously, when a major new ride opens, it tends to be a big draw. However, that Star Wars ride was sold out for the entire day within a few minutes of the park opening. If that keeps happening several months later, then clearly the ride was designed with insufficient capacity.
Spoiler Alert: They haven't.
This is a bit of a pet peeve for me.
It's literally impossible to design every ride to have major capacity.
Any roller coaster you make, regardless of design, is going to have a lower capacity than an omnimover attraction, for example. The loading time takes longer on a roller coaster simply because of the safety features (ie, restraints) necessary for the ride to exist - which you don't have or need on an omnimover attraction.
ROTR, for example, would also be higher capacity if it didn't need its safety features. However, without them, you'd lose several of the highlight features of the ride (mini-spoiler example: the escape pod).
If Guardians were high-capacity, it wouldn't be a roller coaster. It'd be the Peoplemover, Small World, or Carousel of Progress.
With Guardians, they did the best they could under the circumstances: the ride includes two loading bays, which allows them to send trains into the ride alternately, allowing for potentially twice the capacity than a standard coaster (read: Six Flags, Cedar Fair) would have.