how exactly is it a hard problem? You don’t have to rotate the sprite by sining and cosining pixels by hand, you can just render to the same resolution as your sprites and it’ll look fine.
The problem is that most indie games render at 2x or 3x or more natively.
Nearest-neighbour, low-resolution rotation produces unpleasant results when the sprite contains fine details with a thickness of one or two pixels, e.g. outlines: https://imgur.com/a/UiAZ49z
Artistic preferences are subjective, but I expect most players would find that rotated sprite unappealing. This is especially true when the rotation is animated - the aliasing causes a distracting, staticky, random-noise effect which gives the impression that the sprite's fine details are chaotically changing. It's almost the aesthetic opposite of what most pixel artists are aiming for.
That’s the reason why some games use versions of the rotated sprites that have been tweaked by hand. See also tools like RotSprite (http://info.sonicretro.org/RotSprite).
Back in the day I found Privateer's in-game rotations jarring and hideous. Modern games and remasters should at least use higher resolution frame buffers, even if they downscale back to OG--ideally using high color and alpha channels. And I think higher resolution rendering is fine too.
The problem is that most indie games render at 2x or 3x or more natively.