The remaster re-rendered the original cutscenes pretty much intact, but at higher resolution. They look terrible. Why? Because they're higher resolution, but no higher detail. A low resolution video, your brain fills in the details. "There's cracks and crevices in that wall" you think, looking at the blurry image of a stone texture. When it's high res without any filtering or texture improvements, it looks terrible.
The character motion is limited by number of frames. In the original, the characters moved smoothly, pixel to pixel. The low detail art and the low resolution that it was presented at worked because they fit smoothly together. The remaster? High resolution low detail sprites look like they're gliding across the landscape, even though they've got more frames than before.