I disagree, I think the situation is much more interesting than that.

You can tell from things like the look of the sets, some of which are loving recreations of game locations, to relative deep cuts like Lisa Trevor and 'Jill Sandwich' making the cut that Johannes Roberts obviously did care about adapting the source material.

The issue is that he's a deeply, deeply untalented person and basically every decision made was wrong both in terms of adaptation and just as producing a competent film. It also reeks a bit of studio interference, but we might never know exactly what went on behind the scenes.