As long as it's enough for a whole row it's ok for me.
64 chars is enough for unique gfx in three char rows. So we only need around 4 charsets for full screen.
PMs in quad width can cover full width so we get one more color to make gfx even nicer... Far from C64 or Spectrum color attributes color freedom but as the "Tensor Trzaskowskiego" shows it's extra good for puzzle games or similar.
Remember, those modes have been used very often in Basic games, because it offers fast CPU AND GRAPHICS. Using Machine Language offers endless possibilities ... almost