The promise of Luke Skywalker being in the film is more than just the 32 year gap between ROTJ and TFA, it is the promise of the opening line of the crawl. Luke Skywalker is a through line in the film from the VERY start. It’s funny how people say TFA has a cliffhanger, which simply isn’t true. If we DIDN’T see Luke it would have been a cliffhanger. But seeing him is the resolution to the story outlined from the very start, very first line of the crawl. The fact that we know Kylo and the First Order are still out there and Rey has training to do is simply a sequel hook, NOT a cliffhanger.

Han’s capture is an element introduced in the second half of ESB and resolving it in that film would have felt out of place because it wasn’t an integral part of that film’s story from the start. The cliffhanger is justified because it is a plot thread that is introduced near the end of the film and, unlike a plot thread introduced at the very start, wouldn’t reasonably require a resolution at the end of the film.