I'm perfectly fine with that. This is a Superhero Origin movie, all of which (except for Thor 1), were over 2 hours long, and have a build to their final conflict. This movie, based on the trailers, features civilian powers, which they get early on, and they train until the final battle, which is where they get the suits and you have your big climatic finale
It would be incredibly stupid for them to get the suits like 20 minutes into the movie, have a fight scene, and then build to ANOTHER fight at the end of the movie that's no different from the first morphed fight. That's the issue the Transformers movie's had- there was no difference in the action scenes through the whole movie, and it led to them feeling like 6 hour long slogs of movies. Power Rangers seems to be smartly pacing this, buy having all of its big dumb CG saved for the final battle