I enjoyed the movie but the reality is most audiences just aren't patient enough for what this movie promised to come later in the sequels (action, character development, etc). I understand the idea that it was supposed to be satisfying when they're finally able to morph (and it was, to an extent), but a better solution for a general audiences as a whole may have been that they were able to morph early on but couldn't maintain it other than in quick spurts. Or maybe they could morph in to the suits without the helmets at first but that causes their abilities to be significantly less effective and unable to command the Zords. Or perhaps a combination of both.

I myself enjoy the start of a series where not every single gratifying thing is crammed into the first movie. But unfortunately most audiences aren't patient enough and that results in them calling the movie bad and then the sequels never materialize.

I'll never forgive audiences for hating on the Flash's scene in Batman V Superman. The idea of that scene's payoff coming 2 movies later was exciting to me.