They could have done better, but the sculptors were limited by the cost of the final product. They were there not to be artists with freedom, but to translate a movie character into plastic at a predetermined cost. They actually did not like SW figures because they were so boring. Ghostbusters on the otherhand they really liked because of the action features.
The figures had to come from simplest (thus cheapest) of molds that's why every figure is straight-limbed and stiff. To do fancy shapes with undercuts and whatnot the molds would require slides and other expensive features. This was the #1 killer for detail and intricacy.
They were also limited by deco constraints. They only got a few colors per figure. That even translated into modern days. The old school Kenner guys would look at what McFarlane could do with molds and painting and wish they were allowed that freedom. Although McFarlane isn't immune to cost because their toys notoriously came apart. There's always tradeoffs in business.
Kenner's sculptors were talented, but their company was maximizing profits and they had to work within a small window. That's the bottom line. And when they did try to get creative, they'd catch flak from engineering. Like when the guy put bends into the legs of Walrusman, Luke Hoth, and Black Bespin Guard. Just to add some life-like stances to the figures. Believe it or not, he was pushing the limits.
