First, it's a movie where everything needs to be exciting, so that would rob us of the epic ending from a storytelling perspective. Otherwise here's a few ideas...
When trained in the Jedi temple, each Jedi has a specialization and focuses their skills in certain areas.. Darth maul focused solely on lightsaber fighting and was one of the best fighters, but barely had any knowledge of the force in terms of powers other than force push. Jedi healers heal soldiers during wars and sick citizens, but they'd be useless in a fight. Anakin had a more than basic knowledge of the force, such as force lifting people, choke(which is really just doing a force push on both sides of your neck), force push, and great dueling skills.. but he is not a master of the force like Yoda or Sidious is in terms of force powers.. so while he is strong, and we have seen Jedi such as Yoda lift a one man fighter out of a swamp, Vader probably doesn't have the force strength to pull an entire space shuttle out of orbit or maybe lacked concentration to do so(Yoda was alone and focused).
Vader had a 150 lb suit with a respirator and 3 robotic limbs, and pieces keeping him from dying.. the suit greatly diminishes the true strength of Anakin, as he would be a lot more powerful without it. Luke beat him with just a year of training from Yoda and a few years of self taught lessons between episodes 4 and 5, although it could be argued Anakin was battling his feelings as well.
The Disney trilogy in my opinion wasn't well written and overpowered the force on the characters..but she pulled a ship out of anger and used the dark side ,Rey is supposedly extremely strong and could even be a replacement for Sidious.