I still can't decide if it was just a bad movie or satire by someone that didn't quite get how satire works.

It was satire by someone who absolutely understands how satire works. Starship Troopers, the film, is brilliant.

The same director did Robocop, and if you don't get the genius satire of that, then I can't help you.

In fairness, those films can be enjoyed both superficially and as satire.

The film intentionally satirized the book.

The film is a satire of fascists propaganda, and as good satire often it, it is also an good example of fascist propaganda, just like Snow Crash is satire of Cyberpunk while being a good Cyberpunk.

The book isn't exactly fascist though. Verhoeven said he didn't read the book and does not plan to, so he is satirising somewhat superficially.

Heinlein did explore a lot of various political systems in his books, and I think Starship Troopers is focusing most on voter engagement - how people who vote should know something about what they vote on, and that is why only those who served (which includes military but also other "national service" like being a worker colonising planets or postman or whatever) get vote.

Is that fascist? I don't think so. Is it a good political system? I don't think so either but it is a good enough idea for a book.