I can understand how this could be considered a "feature suggestion or change," but I genuinely think this should be considered a bug.
I've included a picture of the textures below, with the current on top and improved below. On the left there's the basic, and on the left I've included a line of "symmetry" (they're not all perfect, but close enough) with a mark to indicate the main center of the pattern (I know it's subjective, this is just for the example).

I created alternate textures for the blue and cyan to better see the underlying pattern that's usually obscured by the diamond and creeper face respectively. Magenta isn't being considered since it very clearly and intentionally has a vertical line of symmetry instead of a diagonal one.

As it stands currently, if I were to make a pattern with lime and then change the terracotta to light grey while keeping the block rotations (blockstates) the same (say, using commands), the pattern would be completely messed up, even though they both have a similar pattern (a quarter of a circle). I've included a picture of a pattern with lime and the same rotations in light grey. As you can see, the pattern's changed.
I just think it's a little unintuitive.