It may be that blue is pervasive, at least in blue-skyed cultures, such that any variations in blue are not that important for tasks such as finding ripe fruits or rancid meats. So then, maybe blue was relegated to the background of consciousness as being unremarkable in itself.
Blue is generally pretty useless, very few natural things are blue in terms of diffuse/albedo hue. I'd accept an assertion that it is largely useless for an animal to distinguish between blue band wavelengths.
