The rotation causing pixel artifacting was never an issue with BW's artstyle, in motion and on a DS screen, it looked perfectly fine.
The problem was backsprites reverting to the Gen 1 mode of being 2x size, so giant pixels.
Simply making the backsprites twice as large wouldnt have helped because the camera zooms out a lot and it would look weird with the front sprites of the opponents.
Really if they hadnt jumped to 3D, I imagine having two sprites for everything, a normal one and 2x res one, and swapping between them on the fly, or using some clever algorithm to blend between them as needed based on camera distance, would have been the logical next step to clean up the visuals.