The series have always felt a bit cheap and the costumes....well theyre not exactly amazing imho. The movie costumes were a real step up. Why didnt they continue (even into the 2nd movie) with those armoured suits? They looked really good.
Because the movie suits were crap and fell apart during the filming of the movie.
Using them in the second movie wouldn't have worked anyway, because it was in the same continuity as the show, not some irrelevant alternate world adventure like the first movie.