Another possibility: we might argue that a proper imitation has to take into account dimensionality, and possibly also temporality (space and time). After all, roses are three dimensional objects in the world.
So, one might say, sculpture is inherently superior to painting on this count.
Furthermore, to properly imitate a rose, we should recognize its fragility. Roses die quickly, relative to other things. So, not only should a proper representation be dimensional, but also in some way demonstrate this fragility.