First about Robocop, meh. It's serious science fiction so it's worth a look purely on the basis that we don't get much of it. It has some interesting satire and like most condemnations of violence it is hideously violent. I don't love the film but I can't help but admit its quality (honestly that's how I feel about most of Verhoeven's work). I haven't seen the sequels.
Now about Starship Troopers. I loathe that movie and I'll admit it's because I love the book too much If you want to like the movie, don't read the book. The movie is an abomination of an adaptation. A complete and utter failure. Not only does it not embrace the themes of the book it seeks to actively contradict them. It feels like a angry fanboy rant; like it's an adaptation by someone who hates what he's adapting.
If I attempt to divorce the movie from Heinlein my intense irritation with it fades a bit. But then it's just a big dumb action movie that (except in a few rare cases) is as subtle as grenade. I appreciate embracing satire, but it seems a bit much when you dress Neil Patrick Harris in (what seems to be) a gestapo uniform, show a news story where the anchor is disembowelled (funny, but not very subtle), and have a coed shower scene. They could have got the same message across without using so large a hammer.
I don't blame you if you like the movie. I admit I might have enjoyed it more if I hadn't read the book first. As it is, every time I think of the movie I am intensely irritated that there are so many people in the world who think that this is all that Starship Troopers is (though the cartoon remedied this ... a very little). It's probably a decent action film in its own right, I just can't get past how bad an adaptation I think it is. It is ballsy that the writer would attempt to argue against Heinlein through adapting Heinlein but I would argue that taking such a position is the very opposite of adaptation. Heinlein would most likely be amused, but I just see red.