I guess the sci-fi examples get a little better when a work makes these things explicitly power armor/tiny mecha. This doesn't fix if there is no room for the drivers arm moving inside the suit's arm, but at least it helps with the "this armor is too thick" part. They're wearing that much armor because they want to be a tank and they can wear it because the inner part of the suit has the strength to carry that armor. (Sure, mecha and power armor have plenty of their own problems, especially at the point where they start getting into the territory of traditional armored vehicles, but that's an other can of worms altogether.)