Allow Channel masking for material Diffuse color

single channel grayscale images appear as RED in Design studio, when applied as Diffuse map. my guess is The default value is Material.R. 

Most of the textures allow channel masking. should be allowed for diffuse also. result should be grayscale render of and chosen channel.

Forcing users to use multichannel textures on diffuse is forcing to use bigger files when comparing one channel to RGB or RGBA.