This would be an option so that it stops biome affecting blocks so that the colour of grass will not change when changing biome and will stay the default plains colour another example would be that leaves don't turn snowy in snow biome
This is useful for big build in a non supercar world
You can easily do this with a resource pack; modify "\assets\minecraft\textures\colormap\foliage.png" to be one color, same for grass (in the same folder), and you can make it any color you want, unlike an in-game setting that just makes it a single biome (I'd prefer the color of forests or jungles). You can make a simple resource pack that only includes these files, in addition to the pack.mcmeta file, which you can copy from the instructions given here, and you can add it to the world by naming it "resources" and placing it in its folder so it will automatically be loaded when you load the world.
Personally, I'd prefer a way to more easily change the colors of individual biomes, which is one reason why I made my own biome color map, which includes biomes like swamps and roofed forest (these use hardcoded colors which can't be changed with a resource pack; water colors and spruce and birch leaves also can't be changed unless you recolor their textures, with a limited range available), though the temperature system that 1.7+ uses would make this a bit problematic (biomes use a range of colors depending on the altitude):