That's not right. I'm an astronomer, and I often look at colour images and colleagues do, too. For example, the galaxies in a cluster of galaxies follow a relation of colours - brightness (the "red sequence"), which can be used to detect the cluster. The eye is also quite good at helping confirm a cluster by spotting the galaxies following this sequence. I also use colour images to help identify spectral changes that change across an image, in my case in the X-ray waveband.