There are many use cases for stepping forwards and backwards between frames in a video; it's not nearly as niche as you suggest :) This is, in fact, far and aw

There are many use cases for stepping forwards and backwards between frames in a video; it's not nearly as niche as you suggest :) This is, in fact, far and away my biggest complaint about VLC. You can say it's slow, but it's just a matter of caching the frames, something that QuickTime seems to have no problem with for the formats it supports.